Study on Microstructure and Mechanical Properties of Particle In-situ Reinforced TiB₂/ZL205A Composites

The particle-reinforced phase was introduced into ZL205 aluminum alloy matrix by mixing TiB₂ salt, the microstructure and mechanical properties of TiB₂ particle reinforced aluminum alloy materials after as-cast and heat treatment were studied. The results show that the basic phase composition of TiB₂ particle reinforced ZL205A composites is α-Al phase,CuAl₂ phase and TiB₂ particles. The endogeneity of TiB₂ particles improves the wettability between the matrix and particles,promotes dispersion, and controls the particle reinforcement size below 1 μm. When the composite billet is extruded, the particles are dispersed by sliding between grains. After extrusion, the heat treatment can promote the further dispersion of particles, improve the agglomeration of TiB₂ particles, and the composites obtain excellent mechanical properties. The ultimate tensile strength, yield strength and elastic modulus of the composites reach 598.0 MPa, 510.0 MPa and 92.4 GPa respectively at room temperature. The ultimate tensile strength of the composites is 197.0 MPa and the elongation is 5.0% at 300℃. Compared with ZL205A matrix, the mechanical properties of the composites are greatly improved.