Enhancing mechanical properties and degradation performance of Mg-0.8wt.%Ca alloy by directional solidification

The mechanical properties and degradation performance in Hank's solution of the directionally solidified (DSed) Mg-0.8Ca (wt.%) alloys were investigated and compared with those of the as-cast alloy. The microstructure was studied by OM, SEM, TEM, and EBSD. It is found that the columnar grains in DSed alloys have a consistent growth orientation of < 11 ($) over bar0 >. The mechanical strength and ductility of Mg-0.8Ca alloy are significantly improved after directional solidification. Besides, the corrosion resistance of Mg-0.8Ca alloy in Hank's solution is dramatically enhanced after directional solidification. The Mg-0.8Ca alloys in Hank's solution mainly undergo microgalvanic corrosion, and the corrosion products consist of Mg(OH)(2), (Ca,Mg)(3)(PO4)(2), and hydroxyapatite (HA). The superior properties of the DSed Mg-Ca alloy are beneficial from the columnar microstructure and the redistribution of the eutectics. The DSed Mg-0.8Ca alloy with columnar dendritic structure is expected to be used as biodegradable materials.

Automated summary

The mechanical properties and degradation performance of directionally solidified Mg-0.8Ca alloy in Hank's solution were studied and compared with those of the as-cast alloy. The columnar grains in the directionally solidified alloy showed a consistent growth orientation. The directional solidification significantly improved the mechanical strength, ductility, and corrosion resistance of the Mg-0.8Ca alloy.