Abstract
Mg–3 wt.%Sn–2 wt.%Ca (TX32) alloy has good corrosion and creep resistance although its strength does not match that of AZ31 alloy. In this paper, the influence of additions of 0.4 wt.%Al and 0.4 wt.%Si on the compressive strength and hot working characteristics of TX32 is reported. Although the room temperature compressive strength improved marginally with the alloying additions, the drop in higher-temperature strength is significant. By comparing with the alloy having only 0.4% Al, it is inferred that the Si addition is responsible for this deterioration. The hot working behavior is characterized by processing maps which revealed that TX32 exhibits two domains of dynamic recrystallization occurring in the temperature and strain rate ranges: (1) 300–350 °C and 0.0003–0.001 s−1 and (2) 390–500 °C and 0.005–0.6 s−1. In Al and Si containing TX32, both the domains moved to higher temperatures and the flow instability is reduced thereby improving the hot workability. In both the domains, the apparent activation energy is 177 kJ/mol, which is higher than that for self-diffusion in magnesium implying that there is a significant contribution from the back stress generated by the hard particles present in the matrix.
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