Effect of thermal and mechanical treatments on the hot working response of Mg-3Sn-1Ca alloy


The effects of homogenization treatment and high-temperature extrusion on the hot working behavior of Mg-3Sn-1Ca alloy have been studied with a view to find an optimum processing route for the manufacture of wrought products. Processing maps and kinetic parameters have been obtained from the flow stress data recorded in hot compression experiments in the temperature range of 300–550°C and strain rate range of 0.0003–10 s–1. These reveal that the homogenization treatment has only a marginal effect on the hot workability, the result attributable to the high thermal stability of CaMgSn particles in the microstructure. High temperature extrusion, however, lowers the hot working temperature significantly (by about 150°C) and this has been attributed to grain refinement during primary processing. The mechanisms of hot deformation remained unchanged by the above treatments and the apparent activation energies for hot deformation are higher than those for self-diffusion suggesting that CaMgSn particles in the matrix cause large back-stress.
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