The Grain Growth of Fe-Cr-Al Alloy and the Rare Earth in Alloy

The experiments have been performed to investigate the grain growth, the characterization of grain boundary migration and the interfacial phenomena at high temperature for Fe-25Cr-5Al-RE alloy. The results show that the rare earth (landium is main) has a certain effect on the grain growth of alloy; La₂O₃ may be the nuclear center of titanium nitride phases that precipitate in the matrix of the alloy; for Fe-Cr-Al-RE (RE<0.1%) fine titanium nitride may precipitate on the grain boundaries and inhibite the migration of grain boundaries; by repeated heating and cooling, the rare earth increases the permeation of O^2- ions through the oxide scale, lanthanum atoms diffuse towards the interfaces and precipitate as lanthana. There is no doubt that the precipitates lanthana and alumina in matrix as a trapping of vacancies greatly increase the oxidation resistance and the life of the electric heating alloy.