Influence of T5 Aging Heat Treatment on Microstructure and Mechanical Properties of as-extrued ZK80 Mg alloy

The micrstructure and mechanical properties of as-extruded ZK80 Mg alloy after artificial aging heat treatment was investigated. The results show that the hardness of the alloy first increases with the increase of time under different aging temperature, and then begins to decrease after reaching the peak value. Under the condition of the same aging temperature and different holding time, the hardness increases gradually with the increase of aging temperature, and then decreases with the increase of aging temperature. The best aging temperature of ZK80 Mg alloy is 180°C, the ultimate comprehensive mechanical properties of ZK80 alloy aging at 180°C for 7h reaches the maximum, which σ_b, σ_0.2, δ, HBR, respectively is 326.7 MPa, 236.7 MPa, 10% and 77.8 HB, and the mechanical properties of untreated extruded state increased by 39.4%, 28.8% and 19%, respectively, The reason is that during the aging treatment, finely dispersed MgZn and MgZn₂ phases are precipitated in the alloy structure, so that the mechanical properties of the extruded ZK80 magnesium alloy are optimized. (paper)