The influence of carbon content on Al-Ti-C master alloy prepared by the self-propagating high-temperature synthesis in melt method and its refining effect on AZ31 alloy

The influence of carbon content on Al-Ti-C master alloy prepared by self-propagating high-temperature synthesis (SHS) in melt method was investigated. The results indicate that when the carbon content in the preform is insufficient, the master alloy mainly contains TiAl3 and TiC phases. With the increasing of carbon content, the TiAl3 phase transforms into TiC particles gradually. Further increase the carbon amount results in the formation of Al4C3 phase. The master alloy with sufficient carbon, which contains Al4C3 and TiC phases, is the most excellent refiner and exhibits satisfactory performance in refining AZ31 alloy. With 1.5% master alloy addition, the grain size reduced from 280 μm to 109 μm. The tensile properties were dramatically enhanced with the refinement of grain structure. The ultimate tensile strength increased from 105 MPa to 156 MPa while the elongation increased from 8.4% to 13.6%.