Effects of Titanium Addition on the Microstructure and Mechanical Behavior of Iron Aluminide Fe₃Al

Abstract

The microstructure, mechanical properties and deformation behavior of four Fe₃Al-based alloys containing 0, 5, 10 or 15 at%Ti were investigated. With the addition of Ti, the coarse-grained microstructure of Fe₃Al was refined and the degree of D0₃ ordering was decreased. Poor bending ductility and a change of fracture mode from cleavage to mixture of intergranular and cleavage were observed in Ti-added alloys. It was shown that the Ti addition decreased the room temperature yield strength, but increased the yield strength at elevated temperatures. Anomalous temperature dependence of yield strength was observed in all the alloys, and the peak strength was shifted to higher temperatures with increasing Ti content. The Ti addition was also revealed to decrease the strain rate sensitivity and activation energy for high temperature deformation. Finally, hot working conditions for the Ti-added Fe₃Al alloys were proposed by taking the stress-strain response, strain rate sensitivity and deformation microstructure into account.