Micromechanical Behavior of Solid-Solution-Strengthened Mg-1wt.%Al Alloy Investigated by <i>In Situ</i> Neutron Diffraction

Abstract

In-situ neutron diffraction experiments were employed to investigate the micromechanical behavior of solid-solution-strengthened Mg-1wt.%Al alloy. Two starting textures were used: 1) as-extruded then solutionized texture, T1, in which the basal poles of most grains are tilted around 70~85° from the extrusion axis, and 2) a reoriented texture, T2, in which the basal poles of most grains are tilted around 10~20° from the extrusion axis. Lattice strains and diffraction peak intensity variations were measured in situ during loading-unloading cycles in uniaxial tension. Twinning activities and stress states for various grain orientations were revealed. The results show that the soft grain orientations, favorably oriented for either extension twinning or basal slip, exhibit stress relaxation, resulting in compressive residual strain after unloading. On the other hand, the hard grain orientations, unfavorably oriented for both extension twinning and basal slip, carry more applied load, leading to much higher lattice strains during loading followed by tensile residual strains upon unloading.