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

• HPT at 20–300 °C results in significant strengthening of magnesium alloy WE43.
• The strength of the HPT processed WE43 alloy is additionally improved by aging.
• Thermal stability of HPT induced hardening does not depend on the HPT temperature.
• HPT accelerates the precipitation during aging irrespective of the HPT temperature.
• Nano-scale grains with the size of 30–100 nm are formed within the twins during HPT.

An age-hardenable Mg-Y-Nd-Zr alloy (WE43) was severely deformed using high-pressure torsion (HPT) at room temperature, 200 °C or 300 °C to refine the microstructure and improve its mechanical properties. Thermal stability of microstructure of HPT processed alloy was studied by monitoring its microhardness and age behavior. The deformation by HPT in the temperature range of 20–300 °C was accompanied by twinning with the twin size of 0.4–8.1 µm. 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 °C.