Influence of a new kind of Al-Ti-C master alloy on the microstructure and mechanical properties of Al-5Cu alloy

The microstructure and mechanical properties of Al-5Cu alloy refined by a new kind of Al-5Ti-0.75C master alloy were investigated. The results show that the master alloy has an excellent grain refining performance on Al-5Cu alloy, and the average grain size of α-Al is reduced from about 1000 μm to 50 μm when 0.2 wt.% of the master alloy was added. It also indicates that the addition of Al-5Ti-0.75C considerably increases the quantity of θ′ precipitates and decreases their sizes during heat treatment process. In addition, the tensile property, hardness and wear resistance of the Al-5Cu alloy are improved markedly after grain refinement. The improved mechanical properties are attributed to a fine equiaxed grain structure of the alloy, a dispersed distribution of second phases and a large number of fine θ′ precipitates.