Evaluation of Ca-alloyed and HAp-reinforced magnesium matrix surface composite properties developed by friction stir processing

The objective of this study is to fabricate AZ31 surface composites (MMSC) through friction stir processing (FSP) by introducing calcium (Ca) as an alloying element and hydroxyapatite (HAp) as reinforcement in different proportions. The analysis reveals that the beta-Mg17Al12 phase remains more stable in its as-fabricated state, while the Mg2Ca phase exhibits greater stability during the aging period. The addition of Ca and HAp leads to higher Mg2Ca and Ca3Mg4Al5 formation during aging process. The incorporation of Ca and HAp results in an increased elastic modulus (E) of the as-fabricated MMSC in comparison to AZ31, with no significant degradation observed following the aging process. The hardness of MMSCs increases with the increase in beta-Mg17Al12, and Mg2Ca phases. Moreover, the incorporation of Ca and HAp results in enhanced corrosion resistance of the as-fabricated MMSCs in comparison to AZ31.