Microstructure evolution of SIMA processed Al2024

Abstract

In this paper, the strain induced melt activated (SIMA) process of A2024 was investigated systematically in order to provide a basis for semi-solid forming of the alloy. To delete the hydrostatic component of stress, the uniform uniaxial compression process is performed. The relation between the grain size and strain before heating is presented and a microstructure evolution model for SIMA is proposed on the basis of experiment. There include two steps in SIMA process. In the first step of plastic deformation, there are two mechanisms to control the deformation, slip or cross-slip or twinning in grain and grain rotation. The deviatory stress will benefit to slip or cross-slip or twinning in grains, and the hydrostatic stress will benefit to rotation of gain. In the second step of heating, the grain boundary will melt first and the shape of the grains will be globe.