Effects of Ca additions on the microstructural stability and mechanical properties of Mg-5%Sn alloy

Mg-Sn based alloys have great potential for high temperature applications because of the formation of the thermally stable Mg2Sn phase in the as-cast condition. In the present investigation, for further enhancement of the mechanical properties, 0.7, 1.4 and 2 wt.% of Ca was added to the base Mg-5%Sn alloy. The dendritic structure of the base alloy was refined after the addition of Ca. It was found that the Mg-5%Sn-2%Ca alloy had the highest hardness, strength, and creep resistance among all tested materials. This is attributed to the higher volume fraction of CaMgSn second phase particles which act as the main strengthening agent in the investigated system. Results also showed that while long-term annealing treatment softened the base Mg-5Sn alloy, there was not much change in the hardness and strength of the Ca-containing materials, implying that CaMgSn intermetallic particles have successfully increased the microstructural stability of the materials. (C) 2010 Elsevier Ltd. All rights reserved.