Effect of plastic deformation on microstructure and hardness of AlSi/Al gradient composites

The effects of plastic deformation on the evolution of microstructure and micro-hardness were studied on plates made from a cylindrical ingot of AlSi/Al aluminum composite. This ingot was produced by double-stream-pouring continuous casting(DSPCC). The results show that the three layers, i.e. the external pure aluminum, internal Al-Si alloy and the transition gradient layer, are maintained after compression as well as rolling processing. With the decrease in thickness of the gradient composite plate, the fluctuation of micro-hardness in transition layer in the direction normal to the applied force is significantly reduced. A simplified lamination model was used to evaluate qualitatively the micro-hardness distribution in the direction parallel to the applied force. However, the model is invalid in the explanation of the fluctuation of the micro-hardness in the direction normal to the applied force. The micro-hardness distribution variation in this direction is mainly attributed to the deformation of α(Al) matrix incorporated the dissolution and spheroidization of eutectic silicon phase.