A simultaneous enhancement of both strength and ductility by a novel differential-thermal ECAP process in Mg-Sn-Zn-Zr alloy

Abstract

Equal-channel angular pressing (ECAP) technique has emerged as a desirable strategy to fairly improve the properties of magnesium (Mg) alloys. However, poor workability of Mg alloys results in the failure of ECAP processing. Herein, a novel differential-thermal ECAP (DTECAP) process, simultaneously endowing Mg-Sn-Zn-Zr (TZK) alloys with good deformability and superior mechanical properties, was developed. Analysis of deformation microstructures of TZK alloys revealed that the excellent comprehensive properties were mainly associated with the activation of non-basal slip, grain refinement, and texture weakening. The results indicated that prismatic<a>slip was predominant deformation mode of DTECAP TZK alloys, which contributed significantly to the improvement of strength and ductility (tensile yield strength of ~311 MPa and elongation of ~20.5%). Moreover, the presence of astonishingly submicron scale grains (down to ~1.35 µm) was responsible for the high strength in DTECAP TZK alloys. In particular, high angular grain boundaries contributed to the highest strengthening effects. Besides, after DTECAP processing, a strong basal<0001>// ND-preferred texture was weakened from 13.48 to 9.38 (m.r.d.), and exhibited ED-split components. The current study can provide beneficial insights into the development of high-performance Mg alloys via DTECAP processing.