The Effect of Gallium on the Microstructure of Superalloy K444

In order to figure out whether Gallium works in the superalloy K444, its composition was modified by adding about 0.003 wt.% and 0.01 wt.% Ga, respectively. Microstructure of the modified superalloy K444 after standard heat treatment was investigated by using optical microscopy(OM),scanning electron microscopy(SEM) and energy dispersive spectroscopy (EDS). The primary dendritic distance of these alloys had no significant changes with the increasing of Ga content, and there were no significant changes for the grain size of the three alloys. The content of eutectic was most in the alloy containing 0.01wt.% Ga, and the morphology of eutectic was most irregular. The segregation of other elements was effected by Ga and the elements of Cr and Zr were segregated seriously in the alloy containing 0.01wt.% Ga.