Processing and microstructure-property relations of high-strength low-alloy (HSLA) Mg-Zn-Ca alloys

Deformation dilatometry and semi-industrial extrusion were used to investigate the effect of different thermomechanical processing routes on the microstructure and mechanical properties of the low-alloy Mg alloys ZX10 (Mg-1Zn-0.3Ca) and ZX00 (Mg-0.5Zn-0.15Ca). It is shown that the deliberately adjusted formation of intermetallic particles beneficially influences dynamic recrystallization and grain growth, with the result of a fine-grained microstructure (grain size < 2 μm). The presence of unrecrystallized regions with its unfavorable influence on ductility and mechanical anisotropy can be controlled by the selection of an indirect extrusion mode. Meta-dynamic recrystallization generates almost fully recrystallized microstructures and hence the desired properties, which are characterized by high strength (yield strength ≈ 240 MPa), simultaneously high ductility (elongation to fracture ≈ 30%), and low structural and mechanical anisotropy. These properties are of great interest for light-weight applications and for deployment as biodegradable implants in medical technology.