气雾化镍基高温合金粉体的过冷度和显微组织特征

Undercooling and Microstructure of Gas Atomized Ni-based Superalloy Powders

摘要:

雾化技术是一种获得微细球形合金粉体的有效方法,其中雾化过程中的过冷度是影响粉体性能的重要因素。本文借助DSC等实验手段,研究了粉体尺寸和冷却速度对粉体过冷度和显微组织的影响,以及粉体尺寸,冷却速度和过冷度直间的关系。结果表明,粉体尺寸和冷却速度越小,粉体冷却时的过冷度越大。同时,较大的过冷度会显著降低粉体中树枝晶的臂间距。另外,粉体尺寸越小,粉体中的胞状晶的比例越高,晶粒的尺寸也显著减小。

Abstract:

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