The addition of third elements may help transform brittle D0₂₂-structured lightweight Al₃Ti to a relatively ductile L1₂-structured (Al, M)₃Ti (where M represents the third elements), thus increasing the ductility at the expense of hardness. Such a transformation could benefit the wear resistance of the alloy due to improved toughness if a proper balance between the hardness and ductility is achieved. In this work, a D0₂₂-predominant Al₃Ti alloy (S-Al₃Ti) and an L1₂-predominant (Al, Fe)₃Ti alloy (S-Al₆₇Ti₂₅Fe₈) were fabricated by arc melting. Change in wear resistance, corresponding to a D0₂₂-to-L1₂ transformation, caused by the addition of Fe as a representative third element, was investigated and compared with the wear resistance of a commercial Al-matrix composite reinforced by 30 wt.% SiC particles (S-Al/SiC_p) as a reference material. It was observed that wear of the S-Al₃Ti resulted from abrasion involving synergistic oxidation, leading to a larger volume loss. In contrast, the softer S-Al₆₇Ti₂₅Fe₈ showed enhanced wear resistance, benefiting from improved toughness with reasonable hardness. During the wear testing, both the alloys exhibited better performance than S-Al/SiC_p, a well-known lightweight composite. This study highlights that D0₂₂-to-L1₂ transformation enhances wear resistance due to increased toughness which can be adjusted using the addition of a third element.

Grain growth of Aluminium alloys at high temperature reduces their strength significantly. Therefore it is essential to control the grain growth by suitable techniques. The effect of Cr on refining the grain structure of Al alloys is investigated in the present work. Cr is added into Al-Si-Mg alloy by stir casting techniques. Subsequently the alloys were subjected to annealing at 500oC for 1 hour to study the grain growth behavior of these alloys. An optical microscope is used to analyze the grain size and microstructure. The mechanical properties of these alloys were studied using a universal testing machine. The Cr additions were varied between 0.5 to 4 weight percent. The Cr addition had shown a significant effect in refining the grain size of Al-Si-Mg alloys. The average grain diameter after annealing was found to be about 151 μm in unalloyed samples while, the 2 wt % Cr added samples showed about 92 μm. The second phase particles, Al₇Cr found precipitated along the grain boundaries apart from Al₂Si and Mg₂Si. However Cr additions more than 2% does not show significant role in refining the grain size. Cr also improved the mechanical properties such as yield strength, ultimate tensile strength and fracture toughness moderately.