Enhancement of mechanical properties in a Mg–Zn–Zr alloy by equal channel angular pressing at warm temperature

Abstract

Equal channel angle pressing was performed to enhance the mechanical properties of an as-extruded heat-treatable Mg–Zn–Zr alloy at a warm temperature of 493 K. Microstructure observations showed occurrence of dynamic recrystallisation and dynamic precipitation after equal channel angle pressing four passes, resulting in an ultrafine grain size of 0.8 μm and a high number density of fine precipitates. A strong texture characterised by a tilt angle of 45° for c-axes relative to the out-extruding direction was formed, producing an obvious improvement of mechanical properties with a fracture elongation of 27.2% and a yield strength of 231.5 MPa. The simultaneous enhancement of both ductility and yield strength should be ascribed to the combined effects of dynamic recrystallisation (DRX)-induced grain refinement, texture softening and dynamic precipitation hardening during equal channel angle pressing.

Keywords:

• Magnesium alloy
• Ductility
• Mechanical properties
• Texture
• Grain size