Effect of hot rolling on microstructure and properties of the ZEK100 alloy

Magnesium is the lightest structural material, but its applications are very limited due to the intrinsic brittleness, which is attributed to the limited number of independent slip systems available at room-temperature. In the present study, accordingly, we investigated the effect of 0.5 wt% Ca addition on the activity of slip systems in AZ31 magnesium alloy (AZ31-0.5Ca). For this purpose, polycrystal plasticity simulation based on viscoplastic self-consistent model was used to simulate the texture of AZ31 alloys (with and without Ca) at 10% tensile deformation, and hence, to predict the relative activities of various slip systems in both alloys. The results confirmed that prismatic slip is the dominated deformation system in AZ31-0.5Ca, leading to a higher ductility as compared to the AZ31 alloy. This, in turn, was attributed to the formation of (Mg,Al)2Ca intermetallic compound due to the Ca addition, as found by microstructural observations using scanning electron microscopy.

Effects of calcium on the activity of slip systems in AZ31 magnesium alloy

In this paper, two kinds of micro-tensile test systems for in-situ Electron Back-Scattered Diffraction (EBSD) are developed to explore the difference in microstructure evolution of AZ31 alloy under biaxial tensile stress state (BTSS) and uniaxial tensile stress state (UTSS). The in-situ EBSD results show that there is an apparent difference of texture evolutions during deformation under BTSS and UTSS and the different responses of tensile twins (TTs) in various stress states are proved to be the main reason. A modified calculation of Schmid factor (SF) for varied stress states further reveals that the distribution of TT SF on {0001} pole figure (PF) determined by BTSS significantly differs from that under UTSS. In addition, the change of stress states also affects the deformation compatibility of TT to slip systems. The poor formability of Mg alloy rolled sheets partly results from the incompatibility between TT and slip systems or tensile twinning under BTSS.

Liwei Lu

Papers

Twinning behaviors of a rolled AZ31 magnesium alloy under multidirectional loading