Fatigue and cyclic deformation behavior of iron aluminide

When iron aluminide (FeAl) is used at elevated temperature, it may be subje ct to cyclic loading that can cause failure by fatigue cracking or by cycli c creep rupture. For engineering design considerations, the fatigue and cyc lic creep behavior must be characterized. In the current research, fatigue experiments were performed on specimens made from FeAl material. The specim ens were tested under constant amplitude cyclic loading in air at temperatu res from 400 to 750 degrees C. The frequency was 0.5 Hz, and the stress rat io (R) was 0.1. Fatigue life and cyclic creep behavior were determined as a function of stress amplitude. Stress-versus-fatigue-life (S-N) curves and stress-versus-cyclic-creep-strain plots were developed at each test tempera ture. In some cases, significant variations in fatigue and cyclic creep beh avior were observed. Based on these observations, specimens were selected f or examination by means of scanning electron microscopy (SEM) and metallogr aphy. Application of the data to design and reasons for variations in mater ial behavior are discussed. (C) 1998 Published by Elsevier Science S.A. All rights reserved.