Undercooling and Microstructure of Gas Atomized Ni-based Superalloy Powders

Atomization is an effective approach to obtain fine and spherical alloy powders. Undercooling is an important factor that can affect the property of powders during atomization. The effects of powder size and cooling rate on the undercooling and microstructure of powders were investigated, and the relation between powder size, cooling rate and undercooling was obtained through DSC. The results show that a small powder size and a low cooling rate will result in a large undercooling. Meanwhile, it is found that when the undercooling is large, the dendrite arm spacing of the particles decreases. The smaller the powder size, the greater the proportion of cellular grains, and the finer the grain size of the powders.