Development of constitutive relationship and processing map for Al-6. 65Si-0.44Mg alloy and its composite with B4C particulates

High temperature flow behavior of Al-6.65Si-0.44Mg (all in wt%) (A356) alloy and A356+5 wt% B4C composite were investigated by compression test at temperatures 470, 500, 530 and 570 degrees C and strain rates 10(-3), 10(-2), 10(-1) and 1 s(-1). Constitutive relationship was established by the prediction of materials constants alpha, beta n, Q and InA. The variations in stable and instable regions of processing map were investigated in A356 alloy and A356+5 wt% B4C composite. It was found that the existence of instability domain for A356 alloy, over the range of temperatures similar to 510-570 degrees C and strain rates similar to 1- 4 x 10(-2) s(-1), was extended to regime of temperatures similar to 470-570 degrees C over the same strain rates upon 5% B4C reinforcement. The microstructural evolutions by stable and instable regions were studied in scanning electron microscope (SEM) and by the electron backscatter diffraction (EBSD) technique. (C) 2016 Elsevier B.V. All rights reserved.