The microstructural evolution was investigated during partial remelting of 6061 aluminum bulk alloy prepared by cold-pressing of atomized alloy powders. Meanwhile, the effect of heating temperature on semisolid microstructure was also studied. It was found that after partial remelted, a semisolid microstructure with small and nearly spherical particles can be obtained. The microstructural evolution can be divided into three stages: the rapid coarsening of grains and powders, the structure separation and spheroidization of powders, and the final coarsening behavior of primary particles. For most of the primary particles (larger than 10 μm) in the semisolid state, one particle originates from one original powder in the cold-pressed bulk alloy. Furthermore, proper elevated the heating temperature is beneficial to obtain ideal semisolid microstructure.
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.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.