Microstructure and mechanical properties of Mg-Al-Ca alloy influenced by SiCp size

Mg-Al-Ca matrix composites reinforced with three sizes (1 mu m, 5 mu m, and 10 mu m) of SiCp were fabricated by stir casting. Then the as-cast ingots were extruded at 400 degrees C with the ratio of 16 at a constant ram speed of 3 mm/s. The results indicate that addition of only similar to 1 vol% SiCp is propitious to promote the nucleation and refinement of Al2Ca phase, which can eliminate the Al2Ca phase's network distribution that appeared in as-cast Mg-Al-Ca alloy. But the nucleation of Al2Ca phase strongly depends on SiCp size. Al2Ca phase nucleates at 5 and 10 mu m SiCp, however, it nearly cover the whole particle as the SiCp size decreases to 1 mu m. Besides, the existence of 5 pm and 10 mu m SiCp is propitious to the fracture of Al2Ca phase, however, the 1 inn SiCp seems ineffective to Al2Ca phase during hot extrusion process. Compared with monolithic Mg-Al-Ca alloy, the as-extruded SiCp/Mg-Al-Ca composites exhibit much higher YS, UTS and theta value. Even though the YS and 9 value increase with decreasing SiCp size, the UTS does not change linearly with them and the reasons are given and analyzed. (C) 2015 Elsevier B.V. All rights reserved.