Fatigue of Lamellar Polycrystals in Gamma Titanium Aluminides

摘要

A study of fatigue damage in lamellar polycrystals of gamma-TiAl based intermetallic alloys have been undertaken. Using electropolished fatigue specimens, it has been found that most of fatigue failures occur due to cracks initiating internally. Surface damage prior to failure has been very minimal. The specimens showed very little change in cyclic stress-strain hysteresis prior to failure. This mechanism of fatigue failure is atypical when compared to most conventional materials, and requires a very careful study both from a fundamental and engineering perspective. A theoretical model was developed to related the microcracks forming in fatigue, to the macroscopic ductility of gamma-TiAl specimens.