Microstructure Evolution of High Zn Content Al-Zn-Mg-Cu Alloy Produced by Spray Forming Technology During the Homogenization Process

High Zn content Al-Zn-Mg-Cu alloys produced by spray forming process have excellent comprehensive properties, but the microstructure evolution during the homogenization is unclear yet. The homogenization process was optimized in present work, and the mechanism of microstructure evolution and phase transition were thoroughly analyzed. With the homogenization temperature increases from 450 degrees C to 470 degrees C, the dissolution degree of nonequilibrium Mg(Zn, Al, Cu)(2) increases significantly, but the overburning occurs in 480 degrees C. During the homogenization process with optimized parameter (470 degrees C/24 h), the morphology of phases along grain boundaries transform from bone-like to intermittent distribution due to the dissolution of Mg(Zn, Al, Cu)(2). Meanwhile, the Mg(Zn, Al, Cu)2 transform to MgZn2, which results in anisotropic lattice contraction along axis-a, and increases the axis ratio from 1.6381 to 1.6453. The formation of S(Al2CuMg) was inhibited due to the insufficient component gradient between Mg(Zn, Al, Cu)(2) and matrix in high Zn content Al-Zn-Mg-Cu alloy. [GRAPHICS] .