Coherent and semi-coherent interfaces induced high strength-plasticity compatibility of (Ti+Al)p/AZ31 composites prepared by laser melt injection

Magnesium matrix composites (MMCs) have the advantages of lightweight properties, excellent mechanical properties, and biocompatibility. To achieve deformation coordination and high strength-plasticity compatibility of MMCs, pure Ti is a good candidate for reinforcement. However, Ti and Mg can neither form solid solution nor undergo chemical reactions. This work proposes a new method based on laser melt injection for preparing (Ti+Al)p/AZ31 composites using commercial hot-rolled AZ31 as the matrix. Pre-mixed Ti and Al particles, which can be quantitatively adjusted, are injected into the laser melting hot-rolled AZ31 matrix. Ti particles are uniformly distributed in the matrix, and a metallurgical bonding with interfacial precipitates between unmelted Ti particles and the matrix is established through the molten Al particles. At the interfaces, Ti/Al3Ti form a coherent orientation relationship, while TiMnSi2/Mg2Si and TiMnSi2/Ti are semi-coherent. The results showed that the YS, UTS and EL of (Ti+6 wt%Al)p/AZ31 composites were 186.6 MPa, 243.6 MPa and 17.2 %, respectively, which were enhanced by 48.2 % and 21.8 % for YS and UTS, compared to AZ31 matrix. Meanwhile, the (Ti+Al)p/AZ31 composites present better wear resistance than that of the hot-rolled AZ31 matrix. The very fine grains of the rapid laser forming process contribute to the excellent comprehensive performance, and the nanoscale precipitates with coherent or semi-coherent interfaces produce strengthening effect.