Surface evolution of Al-Si-Cu alloy in thermal shock under different heating speeds

In order to understand the initial surface damage of Al piston in unsteady thermal environment like knock combustion, T6 heat treated cast Al-Si-Cu alloy was thermal shocked under different heating speeds between room temperature and 450 °C by adjusting the environmental temperature. The surface evolution was mainly characterized in view of roughness, hardness, morphology, texture, phase and element distribution. Results indicated that both the roughness and hardness went up to the maximum and then decreased with rising heating speed. Micro-structure and phase analysis suggested that the interactions of solid phase transition and oxidation with enhancing thermal stress took responsible for the surface evolution.