Effect of rare earth-aluminium additions on the microstructure of a semisolid low carbon Fe-B cast alloy

The present study investigates the effects of rare earth and aluminium on the microstructures of as cast and heat treated semisolid Fe-B cast alloys. The as cast microstructure of the semisolid modified Fe-B cast alloy consists of the eutectic boride, pearlite and ferrite. Moreover, compared to a net-like distribution of the coarse eutectic borides in the ordinary unmodified alloy, the eutectic boride structures in the semisolid modified alloy are greatly refined and less interconnected. After heat treatment, the phases in the semisolid modified Fe-B cast alloy consist of the boride and martensite. The additions of rare earth and aluminium help to promote the formation of the short rod shaped and round borides in the semisolid Fe-B cast alloy during heat treatment. Compared to the ordinary unmodified alloy, there is no significant change in the boride area fraction but an obvious decrease in average boride area in the semisolid modified alloy.