Synchronous improvements of strength, ductility‌ and resistance against hardness degradation during thermal cycling of SiC_p/Al-Si-Mg composites

The balance of strength, ductility and the hardness degradation during thermal cycling limited the application of SiC_p/Al-Si-Mg composites. In this work, various strengthening effects by sub-micron SiC_p were calculated, the substructure evolution during thermal cycling and suppression effects of sub-micron SiC_p on hardness degradation were revealed. The tensile strength and elongation of composites increased by 32 % and 60 % by sub-micro SiC_p addition, which can be attributed to improved thermal mismatch strengthening and grain refinement respectively. During 30–250 ℃ thermal cycling, the dissolution of GP zones in composites led to the hardness degradation, and thermal mismatch strengthening induced by sub-micro SiC_p can compensate for hardness loss and inhibit degradation. According to particle stimulated nucleation of recrystallizations, the sub-micro SiC_p introduced high dislocation density into α-Al, and led to recovery and recrystallization after 800 thermal cycling while the Base composites only presented recovery.