The annealing microstructural evolution of Al-10Zn alloy prepared by continuous extrusion of mixed heterogeneous elemental powders

Abstract

Al and Zn powders in the ratio of 9:1 (wt%) were alloyed into rods with a dense structure by using the continuous extrusion technique. To promote metallurgical bonding of heterogeneous elements, the microstructures of these rods with different holding times (1, 3, and 5 min) at the same annealing temperature were investigated. With the increase of annealing time, the microstructure consisted mainly of ( α -Al) and ( α + η ) phases and an ( α + η )-rich phase. The solid solubility of Zn into Al also gradually increased. The calculated x-ray diffraction (XRD) data showed that the lattice parameter of Al decreased to 4.04793 Å after 5 min of annealing, which was decreased by 0.062% compared to the lattice parameter of Al in the powder state. The microscopic stress and dislocation density of Al were increased by 0.27% and 12.52 × 10 ^14 m ^−2 respectively after extrusion, and the microscopic deformation and dislocation density were decreased to 0.2% and 8.71 × 10 ^14 m ^−2 respectively after being annealed for 5 min. The dislocation density and lattice distortion after annealing gradually decreased with increasing annealing time, and the scanning electron microscopy (SEM) results indicated that the mass percentage of Zn increased with increasing annealing time.

Keywords

• continuous extrusion
• heterogeneous elemental powders
• element diffusion
• dislocation density
• microstructural evolution