Effect of Extrusion Ratio in Hot-Extrusion on Kink Deformation during Compressive Deformation in an aMg/LPSO Dual-Phase Magnesium Alloy Monitored by In Situ Neutron Diffraction

To elucidate the effect of extrusion ratio in hot-extrusion on the deformation behavior during compression of Mg(97)Zn1Y(2) alloy containing about 25-vol% long-period stacking ordered phase (LPSO) in the HCP structured alpha matrix (alpha Mg), in situ neutron diffraction measurements were performed under compressive loading using four types of samples: as cast and after hot extrusion at 623 K with extrusion ratios of 5.0, 7.5 and 12.5. The macroscopic yielding was observed to appear by the occurrence of basal slip of alpha Mg in the as-cast sample and at the onset of twinning in the hot extruded samples. The applied stress to initiate slip, twinning, and kinking increased by hot extrusion and then decreased with increasing extrusion ratio. LPSO shared higher stress than alpha Mg and the ratio to the strength increased as the extrusion ratio increased. In the extruded samples, the phase stress levels in LPSO when kinking initiated were almost the same for the hot-extruded samples, around 580 MPa, regardless of the extrusion ratio.