A New Insight on the Pulverization Mechanisms of FeSi75 Alloy by Understanding Its Solidification Process

Abstract

Easy pulverization of FeSi75 alloy during its crushing, storage, and transportation, inducing huge loss of such alloy annually, has been a critical problem. In this research, the pulverization mechanisms of FeSi75 alloy have been understood by introducing a range of characterization techniques to find out correlations between the alloy microstructure, mechanical properties, formation of PH3, and the pulverization during its solidification process. The experiments are carried out under different isothermal quenching temperatures and casting cooling rates. The results show that during the cooling process, the eutectic reaction occurs and produces the low‐ductility ζ phase, which leads to cracks in the microstructure and higher pulverization possibility. Moreover, sulfides and phosphides precipitate on the Fe‐Si microstructure and form clustered structures, and the release of PH3 increases with decreasing temperature. The internal stresses generate by phase transformations, the low‐ductility ζ phase, and the precipitation of sulfides and phosphides at crack sites collectively lead to the pulverization of FeSi75 alloy. It is also found that the grain size becomes smaller and more uniform at higher casting cooling rates, which effectively prevents the precipitation and enrichment of sulfides and phosphides, reduces PH3 release, and hence could prevent the pulverization of FeSi75 alloy.