Point defect behavior in high temperature region in the B2-type intermetallic compound FeAl

The defect structure was investigated for B2-type Fe1-cAlc alloys (0.44 < c less than or equal to 0.51) by in-situ neutron diffraction measurements in the temperature range from room temperature to 1260-1300 K. Resulting point-defect behavior at high temperatures above about 800-1000 K where additional thermal vacancies are created is summarized as two common features: (1) thermal vacancies are formed on both sublattice sites; (2) antistructure atoms tend to return to their own sublattice sites. The second feature may be due to recovery process of excess antistructure atoms into their right sublattice sites. Based on the first feature, the random vacancy distribution (RVD) process was proposed as an essential defect mechanism in FeAl alloys. Further, the defect type (antistructure defect, triple defect or hybrid types) in these alloys was discussed and as a result it was concluded that the extended hybrid type, including the RVD process, is necessary for better understanding of their defect mechanism. (C) 1998 Published by Elsevier Science Limited. All rights reserved.