Strengthening of age-hardenable WE43 magnesium alloy processed by high pressure torsion

An age-hardenable Mg-Y-Nd-Zr alloy (WE43) was severely deformed using high-pressure torsion (HPT) at room temperature, 200 degrees C or 300 degrees C to refine the microstructure and improve its mechanical properties. Thermal stability of microstructure of HPT processed alloy was studied by monitoring its micro hardness and age behavior. The deformation by HPT in the temperature range of 20-300 degrees C was accompanied by twinning with the twin size of 0.4-8.1 mu m. A very fine grain structure with the average grain size of 30-100 nm was formed, predominantly within the twins, during and after HPT. Severe deformation by HPT resulted in substantial strengthening of the WE43 alloy, especially after processing at room temperature. The strength of the HPT processed WE43 alloy was additionally improved by subsequent aging. It was found that thermal stability of strengthening induced by HPT did not depend on the deformation temperature and sustained to 250 degrees C. (C) 2016 Elsevier B.V. All rights reserved.