Optimizing microstructure and enhancing mechanical properties of Al–Si–Mg–Mn–based alloy by novel C-doped TiB2 particles

Abstract

Grain size, grain orientation, the size and distribution of the precipitated phases are very important for the mechanical properties of particle reinforced aluminum matrix alloys. In this work, the effects of C-doped (C–TiB2) particles on the microstructure and properties of the Al–Si–Mg–Mn alloys were systematically studied. The results show that the as-cast grain size of (C–TiB2)/Al–Si–Mg–Mn alloy is refined to 29.7 μm by 0.5 wt% C–TiB2 particles, and the grain size instability due to static recrystallization can be effectively inhibited in the heat treatment progress after hot deformation, stabilizing the fine grain structure. Furthermore, 0.5 wt% C–TiB2 particles tend to distribute with the AlFeMnSi and Mg2Si phases, refining the size of precipitates. The C–TiB2 particles can also improve the geometrically necessary dislocation density and change the grain orientation of the T6 treated (C–TiB2)/Al–Si–Mg–Mn alloy, thus reducing the average value of the Schmidt factor and increasing the deformation difficulty. The above effects of 0.5 wt% C–TiB2 on the microstructure of the (C–TiB2)/Al–Si–Mg–Mn alloy cause the yield strength and the uniform elongation to synergistically improve by 13.8% and 18.7%, respectively, compared to the matrix alloy.