Influence of process parameters on the characteristics of TiAl alloyed powders by fluidized bed jet milling

Abstract

Micro-fine high Nb containing TiAl alloyed powders were prepared by using fluidized bed jet milling from the pre-crushed Ti–45Al–8.5Nb–0.2W–0.2B–0.02Y(at.%) ingot. The effects of process parameters on the powder characteristics were investigated. The results show that the particle characteristics are mainly determined by classifier frequency. At or above 5600rpm, the ground powders are composed of coarse block-shaped particles and finer flaky debris, with particle number-average diameter lower than 18μm. With the increase of classifier frequency and the decrease of grinding gas pressure, the amount of flaky debris formed under abrasion mechanism gradually increases, which causes the obvious decrease of the powder number-average diameter, distribution uniformity, and sphericity degree. With the classifier frequency of 8400rpm and grinding gas pressure of 0.55MPa, the obtained powders possess the minimum particle size of 5.32μm, with a uniformity level of 0.38 and a Wadell's sphericity factor of 0.820.