2016 Volume 57 Issue 2 Pages 91-98
A novel method, known as powder thixoforming is proposed. The effect of ball milling on the microstructural evolution of a 2024 alloy, prepared by cold pressing ball-milled powders is examined during partial remelting. Additionally the effect of reheating temperature on the microstructure has also been investigated. Results indicate that welding and deformation of the milled powders occurred. A semisolid microstructure with fine spheroidal primary particles results following partial remelting. Microstructural evolution comprises three stages, the rapid coarsening and formation of compact particles, separation of the welded particles with reduction of the particle size, and finally coarsening. Compared with the microstructural evolution of the powder compacts prepared by un-milled powders, the first stage is accelerated, but the second stage is retarded. The microstructural evolution is also accompanied by densification. A suitably elevated temperature is favorable to achieve a compact semisolid microstructure for thixoforming.
