[en] Titanium aluminide alloys based on the α₂ phase were originally developed to extend the application range of titanium by providing improved elevated temperature strength and environmental resistance. These improvements were to come from the much larger concentrations of aluminum added to make these alloys. It was hoped that the increased amount of aluminum would favor the formation of a continuous, environmentally protective layer of alumina, Al₂O₃, at the alloy's surface. Tensile and creep testing these alloys at elevated temperatures (≥∼450 C) in an air environment results in circumferential cracking along the specimen surface. This cracking can lead to premature failure as compared to vacuum testing. Balsone has observed this behavior in Ti-24Al-11Nb tensile tested in air. He repeated the tensile testing in vacuum at 550 C and 650 C, finding that the surface cracking disappeared and that the tensile elongation was significantly increased. From this, Balsone deduced that there was a significant effect of the environment, presumably oxygen embrittlement, on tensile properties at temperatures as low as 550 C. Vacuum tensile testing of Ti-25Al-10Nb-3V-1Mo (Ti-25-10-3-1) also results in a significant improvement in tensile elongation. The intent of the present investigation was to further study the effect of an air environment at elevated temperature on the tensile elongation of Ti-25-10-3-1. In particular, environmentally assisted surface crack growth into the tensile specimen was of interest