111 0 Microstructure, Mechanical, and wear analysis of hypereutectic AlSi composite reinforced with rare earth element OriginalPaper 1 1 2018 Ali M.H. Altameemi Mohd Ayub Sulong Hamidreza Ghandvar Aqeel Ahmed Bhutto Tuty Asma Abu Bakar tuty@utm.my Faculty of Mechanical Engineering Universiti Teknologi Malaysia 81310 Johor Bahru, Johor Malaysia Mechanical Power Technical Engineering Department Al-Amarah University College 62010 Maysan Iraq. Department of Mechanical Engineering School of Engineering, New Uzbekistan University 100000 Movarounnahr Street 1, Mirzo Ulugbek District Tashkent, Uzbekistan Department of Mechanical Engineering MUET SZAB Campus Khairpur Mirs 66020 Pakistan Abstract The strength of hypereutectic AlSi alloy is crucial, and investigations have been conducted to enhance it through various means for a specific application. Different percentage contents from 0.1 to 1.0 wt.% of the rare earth element Gd were added to ADC 14 hypereutectic AlSi alloy. The composite specimens were prepared via controlled stir casting, and mechanical, microstructural, and wear analyses were conducted in accordance with ASTM standards. The experimental results showed that the highest value of ultimate tensile strength (UTS), percent elongation and hardness at 249.59 MPa, 0.062% and 87.6 VHM, respectively, were obtained for a 0.3 wt.% Gd content in the hypereutectic composite. Furthermore, the hypereutectic composite at 0.3 wt. of Gd exhibited better wear rate of and material removal rate. The hypereutectic AlSi composite\'s microstructure showed that the addition of Gd greatly improved the Si particles, making them finer and more equiaxed (m to m ), especially at 0.3 and 0.5 weight percent of Gd. According to the experimental results obtained, the hypereutectic composite\'s mechanical, micro-structural, and wear properties were enhanced 5%, 57% and 17% respectively by the addition of Gd. Keywords ADC14 alloy Gd addition Mechanical Properties Microstructure Analysis Wear Analysis. Introduction AlSi alloys are among the most notable alloys and are utilised in numerous applications ranging from aerospace, automotive, and transportation industries \cite{1}. Silicon (Si) is the primary alloying element in AlSi alloys. The AlSi alloys are classified into three main grades: hypoeutectic (less than 12 wt.%), eutectic (12.3 wt.%), and hypereutectic (more than 12.3 wt.%) based on the weight percent of Si in it \cite{2}. The hypereutectic AlSi alloys provide better results as compared to the other two grades of the AlSi alloys \cite{3}. The higher content of Si is the major reason for the promising results, including improvements in wear resistance, thermal conductivity, dimensional stability, and mechanical strength, of the hypereutectic AlSi alloys. Such content of Si also provides a reduction in the thermal expansion of the component due to its lower coefficient of thermal expansion \cite{4}. However, the presence of Si in the microstructural cast hypereutectic Al–Si alloys results in a complex microstructure \cite{5} because of the occurrence of Si in large size and eutectic morphology \cite{6}. The mechanical strength of hypereutectic AlSi alloys is adversely affected by the coarse morphology of Si in their microstructure. Si\'s coarse morphology has caused the cast alloy to become porous and split, which weakens mechanical and wear behavior of the alloy \cite{7}. The appearance of porosity lowers the hypereutectic AlSi alloy\'s tensile strength, wear resistance, and the ductility \cite{8}. In the microstructural cast hypereutectic Al–Si alloys, the various techniques are employed to improve the morphology of Si \cite{9}. Some of such remarkable maneuvers include the use of heat treatment techniques, incorporating grain refiners, the insertion of ceramic and metallic reinforcements, and regulating the casting parameters 10. These techniques result in improving both of the morphology of Si and the microstructure of the cast hypereutectic AlSi alloys. Scientists have studied the incorporation of ceramic and metallic reinforcements into hypereutectic AlSi composites for decades 11. Rare earth elements (REEs) 12 are the second type of reinforcement material, and they have performed better in Al-based composites 13. In a study, the common REEs, such as Gadolinium (Gd) and Holmium (Ho), were added to an Al-based composite, resulting in a considerable microstructure refinement as a result of the composite\'s lower Si size 14,15. The optical microscopy (OM) images of the Al-based composite showed improvement in grain structure, and mechanical properties were enhanced 16. This confirms the integration of REEs had a substantial impact on the mechanical properties and microstructure of the composite, eventually affecting its applications 17. Numerous investigations have been carried out to examine how adding REEs affects the size, microstructure, mechanical, and tribological characteristics of hypereutectic AlSi composites 18. Researchers have examined the effects of common rare earth elements (REEs) on the alloy\'s microstructure, mechanical characteristics, and Si morphological refinement. These include yttrium (Y) 19, neodymium (Nd) 20, cerium (Ce) 21, lanthanum (La), and Gd 22. Based on the obtained microstructure analysis, the addition of REEs reduced the silicon phase\'s nucleation temperature, which improved the size of Si in the hypereutectic AlSi composite\'s microstructure 23. Z. SHI et al. examined the mechanical, microstructure, and XRD analysis of the A356 alloy through the addition of Gd from . The experimental results revealed that the optimum strength of the A356 alloy was achieved at Gd treated through T6 heat treatment. Besides, incorporation of Gd enhanced the Si phase and grains with primary morphology compared to as-cast A356 alloy. Last but not least, the addition of Gd to A356 alloy was found to significantly impact the microstructure and strength of the alloy 24. Alinan and Rosli added Ho and Gd into the LM30 alloy and investigated its XRD and microstructure. It was concluded that the addition of Ho and Gd changed the microstructure of the LM30 alloy, and there were various crystallographic phases in the XRD pattern due to the addition of the REEs 25. H. Ghandvar et al. studied the consequence of Gd addition in alloy on the mechanical and microstructure of the alloy. The results of those attempts showed that the tension strength of the alloy increased from 47 to 69 MPa, the size of the Si decreased from 49 to 23 m, and the aspect ratio declined from Gd addition in the same alloy. Based on the experimental results obtained, it was deducted that the mechanical properties of the alloy were also decreased beyond 1.0 wt.% of Gd addition 26. The same amalgamated microstructure showed that the coarse dendritic primary Mg2Si had been perfectly truncated into an octahedral shape. When Gd/Sb was added at a weight percentage of 1.5, the size of the Si simultaneously decreased from 40 to 12 m. In addition, eutectic Mg2Si converted from flat plate-like to fibre-like structure while reducing to about from in size. Whereas the tensile power of the mixture raised from to MPa at instantaneous addition of Gd/Sb at 1.5 wt.%. The elongation of the element was also increased from 2.65 to 3.9% at the same weight percentage with the addition of Gd/Sb. Concludingly, the microstructure and the tensile features of the alloy were found to be significantly impacted by the mutual adding of Gd/Sb in Al–15%Mg2Si 27. Wenyi Liu et al. examined the tensile strength, grain-refinement, and eutectic-Si structure alteration of the A356 alloy due to the addition of Gd and/or Zr. The experimental results did not show any noteworthy effect on the same properties of the A356 when Gd and Zr were introduced individually. However, the combined addition of Gd/Zr in Because of improvements in the size of Si and the structure\'s morphology, the A356 alloy demonstrated an increase in its tensile strength. Further, the combined addition of Gd/Zr in the A356 alloys transformed the eutectic Si from flat plate-like to fibrous morphology. Nevertheless, the optimal tensile strength and microstructure of the A356 alloy were achieved with the addition of 0.4Gd + 0.5Zr 28. The above literature shows that hypereutectic AlSi alloys have better performance than the other two categories. The addition of Gd in AlSi alloys showed significant improvement in the microstructure, which ultimately increased the mechanical properties of the alloy. Therefore, this research work explores the effect of different weight percentages of Gd on the microstructure, XRD analysis, mechanical, and tribological properties of the ADC 14 hypereutectic AlSi alloy. Materials and Methods Table 1 lists the chemical alloying elements of ADC 14 hypereutectic AlSi alloy along their weight percentages (wt.%). The commercial casting grade ADC 14 hypereutectic AlSi alloy was purchased from a Malaysian Aluminium Alloy company. The rare earth element Gd was added in powder form at loadings of 0, 0.3, 0.5, 0.8, and 1 wt.% to ADC 14 hypereutectic AlSi alloy. begin{table}[ht] \centering \caption{Chemical Alloying Elements of ADC14 Hypereutectic Aluminum Alloy and (weight %).} \begin{tabular}{l l l} \hline\hline Material & \multicolumn{2}{c}{Amount (weight%)} \& Actual & Standard \\ \hline Ferrous (Fe) & 0.89 & 0.75-1.00\\ Copper (Cu) & 4.10 &4.00-5.00\\ Magnesium (Mg) &0.63 &0.50-0.65\\ Silicon (Si)&17.47 &17.00-18.00\\Tin (Sn) &0.02 & Manganese (Mn) &0.22 & Zinc (Zn) &0.67& Nickle (Ni) &0.05& \\\hline\hline\end{tabular}\end{table} Fabrication of Hypereutectic AlSi Composite The molten stir casting method was applied to fabricate the ADC 14 hypereutectic AlSi composite specimens, applied with several percentile weightages of Gd. The controlled stirer was stiring at 300 rpm, and Gd addition was added in pre-heated condition. The solution heat treatment was performed to relieve internal stresses in the ADC 14 hypereutectic AlSi composite specimens. Mechanical Testing The ASTM E8M-04 standard was used to assess the strength, hardness and percentage elongation of the ADC 14 hypereutectic AlSi composite tensile sample as shown in Fig. 1 The Vickers method was used for hardness in accordance with ASTM E384 standards. The surface of the ADC 14 hypereutectic AlSi composite samples was subjected to a 1000 gf load for 10 seconds using a diamond pyramid indenter that was square in shape and had an included angle of 136° between opposing faces.

Fig. 1 Mechanical Testing Specimen

Microstructural and XRD Analysis Using scanning electron microscopy (SEM), the microstructural characteristics of cast hypereutectic Al–Si alloys. The microstructure of cast ADC 14 hypereutectic AlSi alloy added with different weight percentages of Gd was investigated. Also using the optical microscopy, the impact of Gd on the morphology of eutectic Si in the cast ADC 14 hypereutectic AlSi composites was investigated. To determine how the addition of Gd affected the aluminum grains (-Al) and the refinement of primary phases in the microstructure, SEM images were also examined. The evolution of crystallographic phases in the ADC 14 hypereutectic AlSi composites as a function of Gd content was determined by means of X-ray diffraction (XRD) analysis. The phase changes brought on by the addition of different Gd weight percentages were also investigated using Energy Dispersive X-ray Spectroscopy (EDS). Wear Analysis The wear behavior of the ADC 14 hypereutectic AlSi composite specimens was evaluated using a pin-on-disc wear testing setup. Each composite pin was 8 mm in diameter and 25 mm in length and was slid against a rotating steel disk that was 57 mm in diameter, 8 mm in thickness and HRC 62 hard. The test was conducted with a fixed track radius of 50 mm and sliding speeds between 0.5 and 1.5 m/s, under applied loads ranging from 25 to 75 N. Result and Discussion Tensile Strength of ADC14 Hypereutectic AlSi Composite reinforced with xGd The resulting mechanical properties through different experiments on as-cast ADC14 hypereutectic AlSi alloy and its reinforcement with different weight percentages of Gd are presented in table 2. The results exhibited that Gd accumulation increased the tension strengths of the hypereutectic ADC 14 AlSi composite varieties. The introduction of Gd into the hypereutectic AlSi compound improved the Al-Gd intermetallic phase and, hence, the mechanical properties of the compound 26. The stability and formation phase of Al-Gd were dependent on the processing conditions and composition, which played a significant role in improving the mechanical properties of the composite The second is that the addition of Gd improved the solid-solution strengthening mechanism as it successfully dissolved in the AlSi hypereutectic matrix, thus resulting in the better mechanical performance of the composite 32. In addition to, the introduction of Gd also caused a refinement of the Si grain structure from 42-63 m to 17-22 m, which transformed the coarse plate-like morphology of the eutectic Si into finer fibrous and globular morphology, thus leading to improved mechanical properties. When the Gd content exceeded 0.5 wt.%, the tensile strength of the hypereutectic AlSi composite began to decline, eventually lowered than that of the as-cast hypereutectic AlSi alloy. Experimental attempts revealed that the maximum ultimate tension strength (UTS) of 249.594 MPa was achieved at 0.3 wt.% Gd, representing a 5.2% increase compared to the as-cast ADC14 hypereutectic AlSi alloy. Similarly, Sui et al. reported the highest tensile strength for Al–12Si–4Cu–2Ni–0.8Mg alloys containing 0.3 wt.% Gd at room temperature 35. The observed increase in UTS is attributed to microstructural enhancement and refinement of the Si particle size and morphology within the composite!36,37. At 0.3 weight percent Gd, smaller Si particles have stronger tensile strength and elongation due to their increased resistance to deformation. For Gd-reinforced aluminum composites, however, high temperatures during tensile testing could result in a decrease in tensile strength 38. The UTS for all other Gd concentrations was below that of the as-cast ADC14 hypereutectic AlSi alloy above this ideal threshold, with a steady decline noted up to 1 weight percent Gd. The lowest tensile strength, 19.47% lower than the as-cast ADC14 hypereutectic AlSi alloy, was measured at 1 weight percent Gd.The same trend of results for breaking strength (BS) was observed for the ADC14 hypereutectic AlSi alloy reinforced with Gd. The maximum value of BS was attained at 207.74 MPa for the composite material at 0.3 wt.% of Gd, 6.32 % higher than the value of BS for the as-cast ADC14 hypereutectic AlSi alloy. Furthermore, a decrease in BS was achieved for the composite material beyond 0.3 wt.% of Gd, a lower value than that of 1 wt.% Gd addition in the composite material. However, a continuous decrease in the BS was achieved for the composite material from 0.3 to 1 wt.% of Gd. The stress-strain diagram was plotted from experimental tensile testing, as shown in Fig. 2. A linear relation between stress and strain was observed up to the elastic region. In fact, elongation results show the stretching of the specimen during tensile testing, and their value represents the increment in both the elastic and plastic regions of the composite material 39. According to the elongation values obtained in this study (which are displayed in Table 2), the addition of Gd increased from 0.1 to 0.3 weight. There was a subsequent increase in elongation, after which the hypereutectic AlSi composite\'s elongation steadily declined. The maximum elongation value, which was greater than that of the as-cast ADC14 hypereutectic AlSi alloy, was attained at 0.3 weight percent of Gd. begin{table}[ht] \centering \caption{Mechanical Properties of ADC14 Hypereutectic AlSi Alloy added with different Gd addition.} \begin{tabular}{ l l l l l} \hline\hline makecell{Gd Content\\ (wt.%)}& \multicolumn{4}{c}{Mechanical Properties} \& makecell{Ultimate Tensile\\ Strength(MPa)} &makecell{Breaking \\ Strength (MPa)} &makecell{Elongation\\ (%)} &Hardness\hline0&237.233&195.38&0.0555833&82\\0.1&238.75 &180.81&0.0618967&84.5\\0.3&249.594&207.74&0.0623633&87.6\\0.5&239.185&164.16&0.0559767&85.8\\0.8&212.079&153.75&0.0529667&83.5\\1.0&191.043&141.83&0.0504233&82.7\\\hline\hline\end{tabular}\end{table}

Fig. 2 Stress-Strain Diagram of ADC14 added xGd.

Hardness values of ADC14 alloy with different Gd additions.

Fig. 3 Hardness values of ADC14 alloy with xGd addition.

Fig.3 shows the hardness values of the alloy reinforced with varying weight percentages of Gd. The addition of Gd increased the hardness continuously, with the highest and lowest values of hardness achieved at 87.6% and 82.7%, respectively, for 0.3 wt.% and 1 wt.% of Gd. A total increment of 6.83% was achieved for the composite material compared to the as-cast ADC14 hypereutectic AlSi alloy. Beyond 0.3 wt.% of Gd, the hardness of the composite material continuously decreased with increasing the content of Gd. The increase in the hardness of the composite material is mainly due to the addition of the rare earth element Gd 41. Lu et al. concluded in their research that the addition of Gd had a positive effect on the hardness of the composite 42. These enhancements were largely the consequence of microstructural modifications, such as a round shape and grain size, which limited dislocation movement and enhanced hardness 43. The Gd dissolved in the hypereutectic AlSi matrix, which ultimately improved the resistance to dislocation movement and consequently enhanced the hardness of the composite. The other reasons for the improvement in hardness of the composite specimens include processing parameters 44, enhancement in the Si morphology 45, and refinement of the Si structure and its phase formation within the hypereutectic AlSi matrix due to the addition of Gd in the composite 46. Microstructural analysis of ADC14 Hypereutectic AlSi Alloy with xGd Reinforcement It is commonly known that the size and shape of the constituents, including Si, have a major influence on the microstructure of hypereutectic AlSi alloys. Temperature gradients during melting and freezing rates are the other primary influencing factors. By improving the morphology of Si, heat treatment also significantly alters the microstructure of the hypereutectic AlSi alloy. However, the microstructure of the hypereutectic AlSi alloy is greatly influenced by the size, shape, and morphology of Si. The cast microstructure of the hypereutectic AlSi alloy frequently consists of coarse and segregated primary Si crystals in addition to needle-like eutectic Si. The hypereutectic AlSi alloy\'s strength, ductility, and machinability are all adversely impacted by the coarse primary Si morphology. Therefore, fine and small-sized Si particles are in favour of enhancing the mechanical properties of the hypereutectic AlSi alloy. It is concluded that the addition of Gd in the hypereutectic AlSi alloy can also produce a fine shape of Si particles 24. Thus, in this study, various weight percentages of Gd were added to the hypereutectic AlSi alloy, and scanning electron microscopy (SEM) was used to investigate the composite\'s microstructure. Effect of Gadolinium on Eutectic Silicon Morphology

Fig. 4 Effect of varied loadings of Gd Addition on ADC14 Hypereutectic AlSi.

The as-cast hypereutectic AlSi alloy had dendritic and coarsened primary Si, according to the OM analysis, which had a detrimental effect on the alloy\'s mechanical characteristics (0 weight percent of Gd). Gd improved the mechanical properties of the hypereutectic AlSi composite by refining the size and shape of the primary Si as shown in Fig.4. Primary Si was transformed into a polyhedral primary shape with size refinement upon the addition of Gd. The degree of polyhedral primary Si morphology in the hypereutectic AlSi composite increased as the Gd content rose. Studies reveal that polyhedral primary silicon forms in hypereutectic Al–Si alloys across a broad range of growth velocities. The octahedral form forms the fundamental one for the same alloys. This form of silicon can be observed in a broad range of forms, including the triangular, square, trapezoidal, and hexagonal, because of the due to the arbitrary cutting experienced while polishing of the samples. The octahedral primary silicon is thought to be either homogeneously nucleated on melt solidified at high cooling rates or heterogeneously nucleated on the modified alloys. The intermetallic bonding of Si with aluminium was also observed in the OM images of hypereutectic AlSi composite specimens. Effect of Gd Primary Aluminium Grains and Primary Phase Refinement

Fig. 5 SEM images with Gd additions on Microstructural and fracture variations in ADC14 hypereutectic AlSi alloys.

The primary -Al phase of the as-cast ADC 14 hypereutectic AlSi alloy is dendritic as well as relatively coarse, as shown in the SEM image of it. Further, the large dimension including the coarse Si structure were also observed for the as-cast ADC 14 hypereutectic AlSi alloy. The addition of Gd refined both the size and shape of the -Al phase and the morphology of Si. Z. Shi et al. revealed that the introduction of Gd had a remarkable impact on reviving the phase of the same and modifying the Si phase in the A356 alloy. However, the optimum weight percentage of Gd was between 0.2 and 0.4 wt.% in the A356 alloy 24. This endorsed the highest values of tensile strengths and hardness achieved at 0.3 wt.% of Gd in this research work. The other research work performed by W. Liu et al. mentioned that the addition of Gd refined the primary -Al grains and resulted in some minor changes in Si morphology within the microstructure of the A356 alloy 28. The research work conducted by H. Ghandvar et al. mentioned that the Si size and aspect ratio were improved due to the addition of Gd in Al-18Si alloy 26. The inclusion of 0.8 wt.% of Gd provided the smallest size and more regular shape of Si in the microstructure of Al-18Si alloy, and ultimately provided the highest value of tensile strength of the alloy at 0.8 wt.% of Gd. Y. Sui et al. found that the addition of Gd changed the morphology of Si and modified the Gd-containing phases in the microstructure of the Al–12Si–4Cu–2Ni–0.8Mg alloys. 0.2 wt.% of Gd addition in the same weighted alloys had an optimum refinement effect, and maximum values of thermal strengths were achieved for the alloy. However, beyond , the ductility of the Al–12Si–4Cu–2Ni–0.8Mg alloys was reduced 35. The likely mechanism was that Gd either contributed solute-induced grain refinement (increasing constitutional undercooling during solidification) or formed potent nucleating particles (such as Gd or Gd-containing intermetallics) that promoted the formation of a finer -Al dendritic network. This suggested that the addition of only Gd did not necessarily have a direct and significant impact on the microstructure and mechanical properties of the AlSi alloy. Gursoy Timelli conducted a thermal analysis of an Al–7Si–0.3Mg alloy reinforced with different percentages of Gd. The results showed that the weight percentage from 0.1–0.5% Gd had no significant improvement in -Al grain size under both slow and fast cooling conditions 47. Thus, other strategies, such as adding grain refiners, adjusting casting temperatures (pouring and cooling), and heat treatment, may also be adopted to refine the microstructure of the AlSi alloys. However, the content of alloying elements may decide the potential strategy to improve the microstructure of the AlSi alloys. Figure 5 exhibits the SEM descriptions of the as-cast ADC-14 hypereutectic -AlSi alloy (0% Gd) and ADC-14 hypereutectic-AlSi alloy varied with different weightages of Gd. The SEM image of the as-cast ADC 14 hypereutectic AlSi alloy (0% Gd) showed large, irregular primary Si particles with high aspect ratios ( 1.1–1.62) and a diameter of42–63 m. These irregular Si particles (both primary and eutectic) acted as brittle sites and initiated cracks due to applied loads. The addition of Gd improved the grain refinement effect on the primary silicon phase and altered the eutectic silicon morphology of the ADC 14 hypereutectic AlSi alloy. Even a small Gd addition (0.1 wt.%) began to reduce the Si particle size, and further additions to 0.3–0.5 wt.% Gd led to significantly finer and more equiaxed Si particles. By the optimum intermediate level of \ 0.8 wt.% Gd, the primary Si was refined to approximately 17–27 { }mwith an aspect ratio of approximately 1.1. This indicated that the primary Si transformed from coarse, plate-like or star-shaped crystals into much smaller, more polyhedral grains with nearly rounded morphology at 0.8wt.% Gd, thereby improving the tensile strength and ductility of the ADC 14 hypereutectic AlSi alloy. Furthermore, the eutectic silicon in the ADC 14 hypereutectic AlSi alloy also became slightly finer and shorter with the addition of Gd. These modifications are aligned with the research carried out by H. Ghandvar (2021), where the addition of REEs reduced the eutectic Si from8 to5 { }min size in an AlSi alloy 48. Whereas, the same alloy exhibited over-modification owing to the SEM image at 1 wt.% Gd addition in ADC 14, making the size of Si increased and irregular. This revealed the negative impact of same weighted AlSi alloy on the microstructure of alloy while adding wt.% Gd beyond 0.8. This finding corresponds with the work of H. Ghandvar et al. on ADC14 alloy, where the addition of Gd was shown to primarily refine the primary Si phase and potentially the -Al dendritic matrix grains. In parallel, the eutectic Si was partially refined but not fully converted to fibrous silicon 26. As a rule, strength and toughness both were enhanced by grain size reduction and slight refinement of eutectic Si produced at optimal Gd contents (0.5–0.8%). Conversely, excessive addition (1 wt.%) resulted in coarse particles losing these benefits. X-ray Diffraction Analysis of ADC14

Fig. 6 XRD Analysis of ADC-14 Hypereutectic -AlSi containing 0 wt.% and various wt.% of Gd.

X-ray diffraction (XRD) analysis of the ADC1- hypereutectic-AlSi alloy modified with different percentages of Gd was investigated. This investigation aims to examine the evolution of crystallographic phases in ADC14 hypereutectic Al–Si alloys as a function of gadolinium (Gd) content. Furthermore, the investigation aimed to identify the intermetallic formation, primary and secondary phases, and phase stability of ADC14 hypereutectic Al–Si alloys upon the addition of Gd. Fig. 6 shows the XRD patterns of as-cast ADC-14 hypereutectic- AlSi alloy (0 wt.% Gd) and ADC 14 hypereutectic AlSi reinforced with different weight percentages (wt. %) of Gd. These XRD patterns showed intense peaks corresponding to the face-centered cubic (FCC) aluminum matrix, with the strongest reflection observed at approximately , corresponding to the (111) plane of Al. Secondary peaks appeared at , consistent with the (200), (220), and (311) planes, respectively. These results revealed the dominant presence of -Al phase irrespective of Gd content in the ADC 14 hypereutectic AlSi alloy. XRD patterns also reveal the presence of Si in the as-cast ADC 14 hypereutectic AlSi alloy (0 wt.% Gd) and ADC-14 hypereutectic- AlSi having different weight proportions of Gd. The maximum intensity peaks were observed near , , and , corresponding to the diamond cubic structure of Si. Furthermore, the XRD patterns for 0 wt.% and 0.1 wt.% Gd exhibited strong intensities, suggesting that the prime and eutectic phases of Silicon remain coarse and well-crystallized at low Gd levels. This indicated that the proportion of 0.1-wt.% of Gd in ADC- 14 hypereutectic AlSi did not significantly affect the crystallinity of silicon. However, the addition of 0.3 wt.% Gd resulted in noticeable improvements, as evidenced by a reduction in the Si peaks, consistent with the findings of Bhakar et al. 49. Correlation with SEM observations confirmed that specimens with 0.3 wt.% Gd exhibited a refined Si morphology, reinforcing the improvements indicated by XRD analysis. With increased Gd weightage beyond 0.3 wt.%, new diffraction peaks began to emerge, particularly between , which were absent in the 0 wt.% Gd pattern. Further increasing the Gd content led to the formation of intermetallic compounds, detectable by XRD as new peaks. The presence of Gd also led to changes in the grain structure, such as the transition from epitaxial to equi-axed growth, which can influence the diffraction pattern 50. At 0.8 and 1.0 wt.% Gd, the peaks associated with Gd-rich intermetallic became more intense and better defined. This indicated that at higher concentrations, Gd segregated and reacted with Al and Si to form thermodynamically stable, but mechanically detrimental, secondary phases. This also explained the reduction in mechanical performance beyond 0.3 wt.% Gd, as these intermetallic promoted crack initiation and brittle fracture, as evidenced by fracture surface analysis. Energy-Dispersive X-ray Spectroscopy (EDS) Analysis of ADC14

Fig. 7 EDS mapping of AlSi-Fe-Cu-Gd in ADC14-xGD of 0.1, 0.3, 0.5,0.8, and 1.0 wt.%.

Energy Dispersive X-ray Spectroscopy (EDS) was conducted to investigate the elemental distribution and phase evolution in the ADC14- hypereutectic- AlSi alloy change via varying contents of Gd. Fig. 7 depicts the EDS mapping of the ADC14 hypereutectic AlSi alloy reinforced with varying contents of Gd. The dominant Al and its uniform distribution were observed in EDS mapping for 0.1 wt.% of Gd. Si was observed in discrete islands corresponding to primary and eutectic Si particles. Small traces of Gd were also detected, indicating its presence in a solid solution or as isolated atomic clusters. The same measures for Al and Si were also detected for 0.3 wt.% of Gd, with improved and refined shape. Gd was more visible in the EDS map, with indications of increased clustering. Localized enrichment of Gd suggested early-stage segregation, though no defined intermetallic compounds were observed. This composition marked the transition between solute-level Gd and the onset of solid-state interaction with the matrix. With increasing Gd content, more distinct Gd clusters were observed, particularly near silicon particles and along grain boundaries. This indicated that Gd began to nucleate as discrete phases and may contribute to the formation of Al–Si–Gd ternary compounds. This phenomenon further refined the Si, resulting in a more uniform morphology in the specimen. The ADC 14 hypereutectic AlSi alloy specimen mixed with 0.8 wt.% of Gd showed strong and distinct Gd-rich regions, indicating the presence of Gd-containing intermetallic compounds, most likely . EDS mapping of the ADC14 hypereutectic Al–Si alloy at 0.8 wt.% showed well-separated Al and Si distributions, while Gd was no longer uniformly dispersed but segregated into clearly defined areas. However, large clusters, possibly corresponding to coarse and brittle intermetallic phases of Gd, were observed for the specimen containing 1.0 wt.% of Gd. The higher content of Gd exceeded the solubility limit with the AlSi alloy matrix, and promoted coarse Gd-rich compounds. The over-modification and reduction in mechanical properties are owing to such exceeded solubility and coarse Gd-rich compounds. Wear and Friction Investigation of Hypereutectic-AlSi-Alloy added with xGd

Fig. 8 Weight loss vs wear rate of ADC14-xGd Alloys.

begin{table}[htbp] \centering \caption{Weight loss and wear rate of ADC14-xGd Alloys.} \begin{tabular}{ l l l } \hline\hline {Gd Content (wt.%)} & {Weight Loss (mg)} & {Wear Rate (mg/N.m)} \\\hline0&3.5& \num{7e-4}\\0.1&3.2& \num{6.4e-4}\\0.3&2.9& \num{5.8e-4}\\0.5&3.3& \num{6.6e-4}\\0.8&3.6& \num{7.2e-4}\\\hline\hline\end{tabular}\end{table}

Fig. 9 Variations in Sliding Distance Vs Coefficient of Friction (FOC) for ADC 14 Hypereutectic AlSi enhanced with different Gd contents.

The wear performance of ADC14 hypereutectic Al–Si alloys added with different amounts of Gd was assessed under dry sliding conditions. The tribological behavior, as indicated by weight loss and wear rate of the ADC14 hypereutectic AlSi alloys, was examined. The tribological behavior of the as-cast ADC 14 hypereutectic AlSi alloy, mixed with up to 0.8 weight percentage of Gd, was analyzed and presented here. The summarized test results are presented in Table 3 and Fig. 8. A wear rate of 7 E-4 mg/N·m was found for the as-cast ADC 14 hypereutectic AlSi alloy. Correspondingly, a weight loss of 3.5 mg was found for the as-cast ADC 14 hypereutectic AlSi alloy. These two values were considered the base values for resistance to material removal under applied load. The wear rate and weight loss of the ADC 14 hypereutectic AlSi alloy were continuously decreased with increasing the content of Gd. The maximum reductions of 5.8 E-4 mg/N.m and 2.9 mg for wear rate and weight loss, respectively, were achieved at 0.5 wt.% of Gd. This is corroborated by XRD data, which indicated the emergence of Gd-containing phases such as . While these phases could contribute to hardness, they may also promote abrasive interactions or micro fracturing at the wear interface if not uniformly distributed 19. EDS mapping supported this, showing localized Gd enrichment and early signs of phase coarsening. Beyond 0.5 wt.% of Gd addition, the wear rate and weight loss of the ADC 14 hypereutectic AlSi alloy were increased continuously. They exceeded the base values of the as-cast ADC 14 hypereutectic AlSi alloy. SEM observations beyond 0.5 wt.% composition revealed the presence of coarse and brittle Gd-rich intermetallic compounds concentrated at grain boundaries and phase interfaces. These compounds acted as stress concentrators and fractured easily under load, contributing to the formation of wear debris and increased material loss 51. The loss of matrix continuity and the brittle nature of these phases significantly compromise the tribological integrity of the alloy 52. These results confirmed that optimal Gd reinforcement (0.3–0.5%) improved tribological behaviour through structural refinement, but excessive additions resulted in embrittlement and higher wear. The friction coefficient (FOC) of the as-cast ADC 14 hypereutectic AlSi alloy (0 wt.% Gd) and ADC 14 hypereutectic AlSi reinforced with different weight percentages of Gd is presented in Fig. 9. The as-cast ADC 14 hypereutectic AlSi alloy (0 wt.% Gd) recorded the highest average FOC, fluctuating prominently within the 0.35–0.60 range. This indicated higher adhesive and abrasive wear tendencies due to the presence of coarse Si phases and limited thermal stability at the contact interface 52. The addition of Gd to ADC 14 hypereutectic AlSi alloy improved the friction performance, and a reduction was observed for all specimens reinforced with Gd. The percentage contents of Gd from 0.3 to 0.8 wt.% showed a notable FOC between 0.25 and 0.35 for the ADC 14 hypereutectic AlSi alloy specimens. This result suggested that the optimal Gd content (0.3-0.8 wt.%) facilitated microstructural refinement and promoted the formation of hard intermetallic phases or oxide layers that reduced metal-to-metal contact. Such effects reduced friction and suppressed interfacial instabilities. Beyond 0.8 wt.% Gd, a slight increase in FOC was observed for 1.0 wt.% samples. While still lower than the unreinforced counterpart, the higher Gd content might have contributed to inter-metallic coarsening or particle clustering, potentially leading to localized stress concentrations and increased ploughing resistance. The obtained FOC results suggested that the addition of Gd had improved the FOC and stabilized surface interactions over extended distances, as well as enhanced the tribological performance of the ADC 14 hypereutectic AlSi alloy containing Gd from 0.3 to 0.8 wt.%. Conclusions The utilization of REEs has drawn significant attention to modern material development. The addition of REEs has been demonstrated to enhance the microstructure and mechanical properties of cast AlSi alloys. In this research work, REE Gd was added to the ADC 14 hypereutectic AlSi alloy at concentrations ranging from 0.1 to 1.0 wt.%, and the mechanical properties, microstructure, EDS Analysis, XRD analysis, and tribological performance were examined. The following conclusions have been drawn based on the obtained results: 1. {The addition of Gd in ADC 14 hypereutectic AlSi alloy improved the tensile strengths, and the maximum value of 249.594 MPa was obtained at 0.3 wt.% of Gd. Beyond this percentage, the mechanical strengths were decreased continuously up to 1.0 wt.%.} 2. {The hardness of the ADC 14 hypereutectic AlSi alloy mixed with Gd was increased, and the highest value of 87.6 VHN was obtained for 0.3 wt.% of the Gd. Beyond this percentage, the hardness decreased continuously up to 1.0 wt.%, but remained higher than the value of hardness for the as-cast ADC 14 hypereutectic AlSi alloy.} 3. {The addition of Gd refined the size and shape of primary Si, converting dendritic and coarsened primary Si into a polyhedral shape with a rounded morphology. The -Al grains were refined, and a size reduction was obtained due to the addition of Gd in ADC 14 hypereutectic AlSi alloy. The eutectic Si morphology was also improved to some extent, but not completely fibrous due to the addition of Gd in ADC 14 hypereutectic AlSi alloy.} 4. {The microstructure of the as-cast ADC 14 hypereutectic AlSi alloy consisted of irregular primary Si particles with high aspect ratios ( 1.1 –1.62) and a diameter of42 –63 m. By the optimum intermediate level of0.8 wt.% Gd, the primary Si was refined to approximately 17–27 m with an aspect ratio of approximately 1.1} 5. {The XRD patterns revealed the dominant presence of -Al phase irrespective of Gd content in the ADC 14 hypereutectic AlSi alloy. The XRD patterns also showed the presence of Si in the as-cast ADC 14 hypereutectic AlSi alloy (0 wt.% Gd). The addition of Gd led to the formation of intermetallic compounds, which were detectable by XRD as new peaks. The presence of Gd also led to changes in the grain structure, such as the transition from epitaxial to equiaxed growth, which could influence the diffraction pattern.} 6. { The EDS spectrometer analysis revealed that the addition of Gd resulted in more defined clusters of Gd, particularly in regions near silicon particles and along grain boundaries. The higher content of Gd exceeded the solubility limit with the AlSi alloy matrix, and promoted coarse Gd-rich compounds.} 7. {The wear rate and weight loss of the ADC 14 hypereutectic AlSi alloy were continuously decreased with increasing the content of Gd. The maximum reductions of 5.8 E-4 mg/N.m and 2.9 mg for wear rate and weight loss, respectively, were achieved at 0.5 wt.% of Gd. The percentage contents from 0.3 to 0.8 wt.% of Gd showed notable FOC between 0.25 and 0.35 for the ADC 14 hypereutectic AlSi alloy specimens. The obtained FOC results suggested that the addition of Gd improved the tribological performance of the ADC 14 hypereutectic AlSi alloy, which contained 0.3 to 0.8 wt.% Gd.} Declaration No any financial support was received during preparation of this manuscript. bibliography{References} References: Singhal, Varun and Shelly, Daksh and Babbar, Atul and Lee, Seul-Yi and Park, Soo-Jin (2024) Review of wear and mechanical characteristics of Al-Si alloy matrix composites reinforced with natural minerals. Lubricants 12(10): 350 MDPI Bhutto, Aqeel Ahmed and Wahab, Saidin Bin and Solangi, Faheem Ahmed and Hussain, Fayaz and Zhou, Ding and Khan, TM Yunus and Shaik, Abdul Saddique (2025) Microstructure, mechanical and physical characteristics analysis of ADC14 hypereutectic AlSi composite reinforced with Al2O3. Alexandria Engineering Journal 126: 303--319 Elsevier Ahmed Bhutto, Aqeel. Development of ADC14 hypereutectic ALSi alloy based composite reinforced with SiC, Al2O3 and TiB2 through stir casting. Universiti Tun Hussein Onn Malaysia, 2021 Ahmed, Aqeel and Wahab, MS and Raus, AA and Kamarudin, K and Bakhsh, Qadir and Ali, Danish (2016) Mechanical properties, material and design of the automobile piston: an ample review. Indian Journal of Science and Technology 9(36): 1--7 Bates, William P and Patel, Vivek and Rana, Harikrishna and Andersson, Joel and De Backer, Jeroen and Igestrand, Mattias and Fratini, Livan (2023) Properties augmentation of cast hypereutectic Al--Si alloy through friction stir processing. Metals and Materials International 29(1): 215--228 Springer Risse, Jan Henning and Trempa, Matthias and Huber, Florian and H{\"o}ppel, Heinz Werner and Bartels, Dominic and Schmidt, Michael and Reimann, Christian and Friedrich, Jochen (2023) Microstructure and mechanical properties of hypereutectic Al-high Si alloys up to 70 wt.% Si-content produced from pre-alloyed and blended powder via laser powder bed fusion. Materials 16(2): 657 MDPI Yang, Bao-Cheng and Chen, Shuai-Feng and Song, Hong-Wu and Zhang, Shi-Hong and Chang, Hai-Ping and Xu, Shi-Wen and Zhu, Zhi-Hua and Li, Chang-Hai (2022) Effects of microstructure coarsening and casting pores on the tensile and fatigue properties of cast A356-T6 aluminum alloy: A comparative investigation. Materials Science and Engineering: A 857: 144106 Elsevier Islam, Md Aminul and Farhat, Zoheir N (2011) Effect of porosity on dry sliding wear of Al--Si alloys. Tribology International 44(4): 498--504 Elsevier Jin, Su-Ji and Shin, Jungho and Bang, Jong-Won and Kim, Yoon-Jun and Jung, Hyun-Do and Kim, Moon-Jo (2024) Refinement of Primary Si Phase in Hypereutectic Al--Si Alloy by Electrically Assisted Solidification with P Addition. Advanced Engineering Materials 26(21): 2401025 Wiley Online Library Elambasseril, Joe and Benoit, Michael J and Zhu, Suming and Easton, Mark A and Lui, Edward and Brice, Craig A and Qian, Ma and Brandt, Milan (2022) Effect of process parameters and grain refinement on hot tearing susceptibility of high strength aluminum alloy 2139 in laser powder bed fusion. Progress in Additive Manufacturing 7(5): 887--901 Springer Kumar, PK Dinesh and Gnanaraj, S Darius (2024) Studies on Al-Si based hybrid aluminium metal matrix nanocomposites. Materials Today Communications 38: 108132 Elsevier Jing, Hui and Geng, Laiyao and Qiu, Shaoyu and Zou, Huawei and Liang, Mei and Deng, Dan (2023) Research progress of rare earth composite shielding materials. Journal of Rare Earths 41(1): 32--41 Elsevier Zhang, Baiqiu and Liu, Kun and Li, Jie and Chen, Bingbing and Huang, CJ and Soboleva, Natalia (2025) A comprehensive review on the rare earth elements improving microstructure and properties of laser cladded coatings. Journal of Alloys and Compounds : 181761 Elsevier Kumar, Abhishek and Choudhari, Amit and Gupta, Ashish Kumar and Kumar, Avinash (2024) Rare-Earth based magnesium alloys as a potential biomaterial for the future. Journal of Magnesium and Alloys 12(10): 3841--3897 Elsevier Xiang, Dingding and Wang, Di and Zheng, Tingfang and Chen, Yu (2024) Effects of rare earths on microstructure and wear resistance in metal additive manufacturing: A review. Coatings 14(1): 139 MDPI Liu, Jin-Song and Yu, Wen-Xin and Chen, Da-Yong and Wang, Song-Wei and Song, Hong-Wu and Zhang, Shi-Hong (2025) A Review of Studies on the Influence of Rare-Earth Elements on the Microstructures and Properties of Copper and Copper Alloys and Relevant Applications. Metals 15(5): 536 MDPI Qinglin, Li (2013) Effects of rare earth Er addition on microstructure and mechanical properties of hypereutectic Al-20% Si alloy/Qinglin Li, Tiandong Xia, Yefeng Lan, Pengfei Li, Lu Fan. Mater. Sci. Eng. A 588: 97--102 Li, Li and Nam, Nguyen Dang (2016) Effect of yttrium on corrosion behavior of extruded AZ61 Mg alloy. Journal of Magnesium and alloys 4(1): 44--51 Elsevier Baysal, Erhan and Ko{\c{c}}ar, O{\u{g}}uz and Kahr{\i}man, Fulya and K{\"o}kl{\"u}, U{\u{g}}ur (2025) Investigation of Microstructure, Hardness, Corrosion and Machinability Properties of Commercially Pure Aluminum alloyed with Rare-Earth Elements. International Journal of Metalcasting : 1--21 Springer Mingbo, YANG and Caiyuan, QIN and Fusheng, PAN and Tao, ZHOU (2011) Comparison of effects of cerium, yttrium and gadolinium additions on as-cast microstructure and mechanical properties of Mg-3Sn-1Mn magnesium alloy. Journal of Rare Earths 29(6): 550--557 Elsevier Wu, Jin Hu and Zhang, Shi Hong and Chen, Yan and Li, Hai Hong and Liu, Jin Song (2017) Effects of La microalloying on microstructure evolution of pure copper. Trans Tech Publ, 361--366, 898, Materials Science Forum Tong, Xian and Zhu, Li and Wang, Kun and Shi, Zimu and Huang, Shengbin and Li, Yuncang and Ma, Jianfeng and Wen, Cuie and Lin, Jixing (2022) Impact of gadolinium on mechanical properties, corrosion resistance, and biocompatibility of Zn-1Mg-xGd alloys for biodegradable bone-implant applications. Acta Biomaterialia 142: 361--373 Elsevier Cheng, Zijian and Yan, Hong and Zhang, Shuqing and Zou, Xiuliang and Cao, Chuanliang (2024) Effect of rare earth La on microstructure, hardness and corrosion resistance of A356 aluminum alloy. Metals and Materials International 30(9): 2490--2502 Springer Zhiming, SHI and Qiang, WANG and Yuting, SHI and Ge, ZHAO and others (2015) Microstructure and mechanical properties of Gd-modified A356 aluminum alloys. Journal of Rare Earths 33(9): 1004--1009 Elsevier Alinan, Ali Luqman and Ahmad, Rosli (2024) The Effect of Rare Earth Elements Holmium, Gadolinium and Zinc on Microstructure of Aluminium LM30 Alloy. Research Progress in Mechanical and Manufacturing Engineering 5(2): 109--111 Ghandvar, Hamidreza and Idris, Mohd Hasbullah and Ahmad, Norhayati and Emamy, Massoud (2018) Effect of gadolinium addition on microstructural evolution and solidification characteristics of Al-15% Mg2Si in-situ composite. Materials Characterization 135: 57--70 Elsevier Ghandvar, Hamidreza and Idris, Mohd Hasbullah and Bakar, Tuty Asma Abu and Nafari, Afshin and Ahmad, Norhayati (2020) Microstructural characterization, solidification characteristics and tensile properties of Al--15% Mg2Si--x (Gd--Sb) in-situ composite. Journal of Materials Research and Technology 9(3): 3272--3291 Elsevier Liu, Wenyi and Xiao, Wenlong and Xu, Cong and Liu, Maowen and Ma, Chaoli (2017) Synergistic effects of Gd and Zr on grain refinement and eutectic Si modification of Al-Si cast alloy. Materials Science and Engineering: A 693: 93--100 Elsevier Bhutto, Aqeel Ahmed and Saleem, Mohammad and Ali, Tahir and Solangi, Faheem Ahmed and Memon, Yasir Aftab and Ahmed, Fayaz (2023) Mechanical Analysis of Downsized Automobile Piston through Simulation. Quaid-e-Awam University Research Journal of Engineering Science and Technology 21(1): 99--104 Ahmed, Aqeel and Wahab, MS and Raus, AA and Kamarudin, K and Bala, AS and Ramli, Mohd Badli (2018) Mechanical And Thermal Issues In Downsize Engine: A Review. International Journal of Engineering & Technology 7(4.36): 475 Ahmed, Aqeel and Wahab, MS and Raus, AA and Kamarudin, K and Bakhsh, Qadir and Ali, Danish (2016) Thermal effect on the automobile piston: A review. Indian Journal of Science and Technology 9(36): 1--7 Elgallad, EM and Ibrahim, MF and Doty, HW and Samuel, FH (2018) Microstructural characterisation of Al--Si cast alloys containing rare earth additions. Philosophical Magazine 98(15): 1337--1359 Taylor & Francis Nanda, Is Prima and Ghandvar, Hamidreza and Idris, Mohd Hasbullah and Hanif, Auliya and Arafat, Andril (2020) Role of Gd addition on machinability of Al-15% Mg2Si in-situ composite during dry turning. Communications in Science and Technology 5(2): 65--69 Du, Andong and Lattanzi, Lucia and Jarfors, Anders Wollmar Eric and Zheng, Jinchuan and Wang, Kaikun and Yu, Gegang (2021) On the hardness and elastic modulus of phases in SiC-reinforced Al composite: Role of La and Ce addition. Materials 14(21): 6287 MDPI Sui, Yudong and Wang, Qudong and Liu, Teng and Ye, Bing and Jiang, Haiyan and Ding, Wenjiang (2015) Influence of Gd content on microstructure and mechanical properties of cast Al--12Si--4Cu--2Ni--0.8 Mg alloys. Journal of Alloys and Compounds 644: 228--235 Elsevier Zhang, Rui and Wang, Shuai and Lu, Weihang and Sun, Fengbo and Huang, Lujun and Bolzoni, Leandro and Geng, Lin and Yang, Fei (2023) Enhancing microstructure refinement and strengthening efficiency of TiBw/near -Ti composites by combining solid-solution treatment with hot processing. Composites Part B: Engineering 257: 110696 Elsevier Wang, ZJ and Zheng, Z and Fu, MW (2024) Aluminum matrix composites: Structural design and microstructure evolution in the deformation process. Journal of Materials Research and Technology 30: 3724--3754 Elsevier Saba, N and Jawaid, M and Sultan, MTH (2019) An overview of mechanical and physical testing of composite materials. Mechanical and physical testing of biocomposites, fibre-reinforced composites and hybrid composites : 1--12 Elsevier Efron, Nathan Rigid Lens Materials. Contact Lens Practice, Elsevier, 2024, 122--130 Zhao, Yang and Zhang, Dingfei and Lei, Renjie and Wang, Peng and Feng, Jingkai and Chen, Xia and Jiang, Bin and Pan, Fusheng (2020) Effect of Gd addition on the microstructure and age hardening behavior of Mg-6Zn-1Mn-4Sn (wt.%) alloy. Journal of Materials Research and Technology 9(6): 12737--12746 Elsevier Lu, Yiyi and Huang, Yuanding and Bode, Julia and Vogt, Carla and Willumeit-R{\"o}mer, Regine and Kainer, Karl Ulrich and Hort, Norbert (2022) Effects of minor gadolinium addition and T4 heat treatment on microstructure and properties of magnesium. Advanced Engineering Materials 24(12): 2200966 Wiley Online Library Ponhan, Kowit and Jiandon, Porawit and Juntaracena, Komkrit and Potisawang, Charinrat and Kongpuang, Manwika (2024) Enhanced microstructures, mechanical properties, and machinability of high performance ADC12/SiC composites fabricated through the integration of a master pellet feeding approach and ultrasonication-assisted stir casting. Results in Engineering 24: 102937 Elsevier Liu, Quan and Chen, Xiaomi and Liu, Kun and Cristino, Valentino AM and Lo, Kin-Ho and Xie, Zhengchao and Guo, Dawei and Tam, Lap-Mou and Kwok, Chi-Tat (2024) Influence of processing parameters on microstructure and surface hardness of hypereutectic Al-Si-Fe-Mg Alloy via Friction Stir Processing. Coatings 14(2): 222 MDPI Li, Yang and Jiang, Ying and Liu, Bin and Luo, Qun and Hu, Bin and Li, Qian (2021) Understanding grain refining and anti Si-poisoning effect in Al-10Si/Al-5Nb-B system. Journal of Materials Science & Technology 65: 190--201 Elsevier Wang, Dong and Jiang, Cuncai and Cai, Gangyi and Li, Jun and Hui, Yanbo and Guo, Yonggang and Ba, Fahai (2025) Refinement of Primary Si in Hypereutectic Al-Si Alloy by Serpentine Channel with Spoiler. Journal of Materials Engineering and Performance 34(3): 2681--2689 Springer Gursoy, Ozen and Timelli, Giulio (2024) The influence of Gd content on the solidification and microstructure of AlSi7Mg0. 3 casting alloy. Journal of Thermal Analysis and Calorimetry 149(8): 3125--3139 Springer Ghandva, Hamidreza and Ali, Saif Yasir and Yajid, Muhamad Azizi Mat (2021) Effect of Gd Addition on Microstructural and Mechanical Properties of Al-18% Si Alloy for Automotive Applications. Journal of Advanced Research in Applied Mechanics 87(1): 1--10 Bhakar, Ashok and Srivastava, Himanshu and Tiwari, Pragya and Rai, SK (2024) Bimodal microstructural characterization of Si powder using X-ray diffraction: the role of peak shape. Powder Diffraction 39(3): 119--131 Cambridge University Press Jiang, Y and Tang, H and Li, Z and Zheng, DD and Tu, YX. Additive manufactured Mg-Gd-Y-Zr alloys: effects of Gd content on microstructure evolution and mechanical properties. Addit Manuf. 2022; 59: 103136. 2022 Chang, Jun Zhe and Ghandvar, Hamidreza and Bakar, Tuty Asma Abu (2024) Effect of erbium and praseodymium addition on wear properties of Al-15% Mg2Si in-situ composite. Materials Today: Proceedings 110: 153--157 Elsevier Zhu, Jia--Ning and Zhou, Ting--Ting and Zha, Min and Li, Chao and Li, Jie--Hua and Wang, Cheng and Gao, Cheng--Long and Wang, Hui--Yuan and Jiang, Qi--Chuan (2018) Microstructure and wear behaviour of Al-20Mg2Si alloy with combined Zr and Sb additions. Journal of alloys and compounds 767: 1109--1116 Elsevier Valizade, Nima and Farhat, Zoheir (2024) A review on abrasive wear of aluminum composites: mechanisms and influencing factors. Journal of Composites Science 8(4): 149 MDPI Additional Files Additional file 1 Additional file 2 Additional file 4 Additional file 6 Additional file 7 Additional file 8 Additional file 9 Additional file 10 Additional file 11 Additional file 12 Additional file 15 Additional file 16 Additional file 17 Additional file 18 Additional file 19 Additional file 20 Additional file 21 Additional file 22 Additional file 23 Additional file 24 Additional file 25 Additional file 26 Additional file 27 Additional file 28 Additional file 29 trueYes