Reduction of primary creep in TiAl alloys by prestraining

The reduction of primary creep is important for TiAl alloys. In addition to previous alloying and microstructure-controlling investigations, this study demonstrates that primary creep of TiAl alloy can also be significantly reduced by a prestraining technique. When the material was first deformed at higher stresses for a few per cent strain, it did not begin to creep at a subsequent stress lower than a critical level, even after one week under load. This behaviour is in strong contrast to that exhibited by the material without prestraining under otherwise identical conditions. The origin of this prestraining effect may stem from the observed feature that creep of TiAl alloys is recovery-controlled at low stresses. The prestraining technique may be of technological importance for prolonging the service life of a potential TiAl alloy component.