The fatigue crack propagation resistance of a lamellar TiAl-alloy has been investigated.It has been proved to be slightly influenced by temperature in air and in vacuum,suggesting that the effect of the ductile-Brittle Transition is not highly pronounced.Fractographic observations supported this point.Crack closure has been shown to play a significant role whatever the temperature.However,the influence of oxide-induced closure is reduced even at 750 and 800 deg C.Finallly,fatigue cracks propagate much faster in air than in vacuum at all temperatures.Details concerning the embrittling mechanisms at room and elevated temperature are discussed.
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