Effect of Precipitates in Mg−Sm Alloys on Their Deformation Behavior and Yield Asymmetry

Abstract

The strengthening effect of precipitates in a Mg−0.4Sm (wt%) alloy on dislocation slip and extension twinning (ET) is evaluated by experimental work and viscoplastic self‐consistent (VPSC) modeling. Experimental results reveal that the extruded Mg−Sm alloy consists of rare‐earth texture (<−12−11> // ED) and extrusion texture (<−12−10> // ED) components. After aging precipitation, tensile yield stress is more effectively enhanced than compressive yield stress. Transmission electron microscopy (TEM) analysis confirms that the precipitates in the aged Mg−Sm alloy are of β′ with an orthorhombic crystal structure. The introduction of β′ precipitates in the compression sample stimulates a higher fraction of extension twins. VPSC modeling indicates that the critical‐resolved shear stresses (CRSS) for prismatic slip, pyramidal <c + a> slip, and basal slip are increased by 75, 30, and 6 MPa, respectively, by aging precipitation, while the precipitation strengthening on ET is negligible. By preferentially hardening against prismatic slip, the compressive and tensile yield asymmetry are increased for the aged Mg−Sm alloy.