Structure and mechanical properties of Mg–Zn–misch metal alloys solidified at different cooling rates

The influence of cooling rate on the mechanical properties and structure evolution of Mg–Zn–misch metal alloys has been investigated. The sequence of structural changes has been correlated with stress—strain curves determined from high temperature uniaxial compression tests. Two regions of work hardening have been identified on the stress—strain curves, described by the Ludwigson equation σ=K ₁ ϵⁿ¹±Δ. Microstructural examination at various levels of deformation has been carried out on selected specimens. In the first region of deformation, the appearance of traces of slip lines was observed inside the grains. In the second region, a network of eutectic precipitates located around the grains had undergone fragmentation, enabling the propagation of deformation by transcrystalline slip across two or more grains. Based on results of the present investigation, optimal properties of the alloys for application at elevated temperatures have been established.