Effect of Fe-B and Fe-C Master Alloy Powders on the Liquid Phase Sintering of Fe-Mo-B-C Sintered Steels

摘要

The effect of addition of Fe-B and Fe-C master alloy powders on the sinteringbehavior, microstructure and densitification of Fe-Mo-B-C sintered steels has been investigated. Addition of B and C in the form of Fe-B and Fe-C master alloy powders to produce Fe-Mo-B-C sintered steels can activate the sintering process by liquid phase sintering. The formation of the first liquid phase is due to the ternary reaction gamma-Fe + Fe2B + Fe3(B,C) -> L. The temperature of the first liquid phase formation depends on the amount of Fe2B and Fe3C phases in the sintering system. For a Fe-1.2 wt% Mo-0.2 wt% B-0.5 wt% C sintered steel this reaction starts at about 1090 degrees C, with the maximum shrinkage rate of 6x10(-5)s(-1) at about 1120 degrees C. In the case of absence of enough Fe3C phase, this will lead to the formation of a second liquid phase due to the binary eutectic reaction gamma-Fe + Fe2B -> L.