Microstructure and tensile properties of in-situ TiAl nanoparticles reinforced AZ31 composites

Abstract

The good interfacial bonding between reinforcements and magnesium (Mg) matrix is the essential requirement for the development of magnesium matrix composites (MMCs) with high performance. Herein, this work tries to improve the interfacial bonding of MMCs. Here, the pre-dispersed Ti nanoparticles were introduced in AZ31 composites to form in-situ TiAl nanoparticles, and the AZ31 composites were synthesized by semisolid stirring assisted ultrasonic vibration method. Microstructural analysis reveals that the TiAl nanoparticles are in-situ formed by the Al atoms in composites diffusing into Ti nanoparticles, and the composites obtain a strong interfacial bonding between the TiAl nanoparticles and matrix owing to the formation of TiAl/Mg semi-coherent interface. The composites achieve simultaneous improvement of strength and plasticity. The composite with 0.2 wt% Ti nanoparticles addition possesses the best comprehensive tensile properties. The corresponding ultimate tensile strength and elongation reach 315 MPa and 21.3 %, respectively. The enhanced strength is owing to dislocation strengthening, grain refinement strengthening, and Orowan strengthening. The good plasticity is the result of the activation of non-basal dislocations, refined grains, weakened texture, and good interfacial bonding.