Enhancing mechanical properties and degradation performance of Mg-0.8wt.%Ca alloy by directional solidification
(1. Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China;
2. School of Materials Science and Engineering, University of Science and Technology of China, Shenyang 110016, China)
2. School of Materials Science and Engineering, University of Science and Technology of China, Shenyang 110016, China)
Abstract: 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 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.
Key words: Mg-Ca alloy; directional solidification; microstructure; mechanical properties; degradation performance