Influence of Ti particle sizes on microstructure and mechanical behaviors of AZ91-Ti composites under different loading paths

Abstract

Magnesium (Mg) matrix composites are recognized as the most promising light structural materials and have been extensively investigated, but they still suffer from a relatively low ductile nature which seriously affects their further development. Herein, the Mg–9Al–1Zn (AZ91) Mg matrix composites with different sizes of Ti particles reinforcement can be obtained via hot pressed sintering followed by hot extrusion. The microstructure demonstrated that the interfacial region is consisted of Mg17Al12 and Al-rich phase. Uniaxial tensile experiments revealed that the AZ91-Ti (particle size of 15 μm) composite achieves the optimal comprehensive mechanical properties, and the corresponding yield strength (YS), ultimate tensile strength (UTS), elongation (EL) of the composite can reach the high values of 210 MPa, 310 MPa, 15.5%, respectively. Moreover, with the decrease of Ti particle size, grain refinement and the strong interfacial bonding between Ti particles and Mg matrix render as-prepared the composites exhibited outstanding mechanical properties. Ti reinforcement particles of appropriate size can alleviate the plastic strain accumulation during the tensile and compressive cyclic loading, so that the excellent ductility of the composite is obtained. Constitutive relation of AZ91-Ti composites in this experiment can be derived from the nonlinear elastic relation. The simulated stress-strain curves of the composites reinforced by Ti particles with different sizes are consistent with the experiment.