Influence of Ti-6Al-4V particles on the interfacial microstructure and strength-ductility synergetic mechanism of AZ91 magnesium alloy

Abstract

Although magnesium (Mg) matrix composites have been intensively investigated as promising light structural materials, their relatively low ductile nature limits their wide-scale applications. In this study, Mg-9Al-1Zn (AZ91) Mg matrix composites reinforced by Ti-6Al-4V (TC4) particles were prepared via powder metallurgy. Microstructure observation showed that the interfacial zone is composed of Mg17Al12 and Al-rich phase. The tensile tests suggested that the yield strength, ultimate tensile strength, and elongation display peak values (211 MPa, 303 MPa, 18.7%, respectively) when the content of TC4 particles is 5 wt%. The improvement of mechanical properties can be attributed to the strong interfacial bonding between the Mg matrix and TC4 particles through the formation of coherent interfacial bonding of Al3Ti/Mg21(Zn, Al)17 and semi-coherent interfacial bonding of Mg21(Zn, Al)17/Mg. The strain distribution during the tensile test of the composite was investigated by using digital image correlation technology. The introduction of TC4 reinforcement can relieve the stress concentration and the composites achieve comprehensive mechanical properties with high strength and high plasticity. TC4 particles can improve the matrix strengthening effect by increasing the work hardening capacity. The elongation of the composite increases during tensile loading.