Of Ni <sub> 3 </ Sub> Al Alloy Thermal / Mechanical Fatigue Crack Extension Behavior

In this paper,the experimental study and the macro-micro analysis about thebehavior of thermal-mechanical fatigue (TMF) crack growth were conducted inNi₃Al intermetallic compound IC10 superalloy, which is candidate material for theheat components of high thrust-weight aeronautical engine with thermal cycle of450℃ to 990℃. It was investigated that the effects of phase angle, load-hold,temperature and frequency on thermal-mechanical fatigue crack growth rate in IC10superalloy, respectively A predictable model about thermal-mechanical crackgrowth rate in IC10 superalloy is proposed.The key results drawn from this study are as follows: Increasing temperatureand decreasing frequency accelerate crack growth rate;The crack growth rate of in-phase thermal-mechanical fatigue is much larger than that of out-phase thermal-mechanical fatigue and both of them are between the crack growth rates of 450℃isothermal and 990℃ isothermal tests; Load-hold also accelerates crack growth.The mechanism of damage under different test conditions is different, for instance,mechanical fatigue, creep-fatigue, creep, and oxidation of high temperature.A linear summation model is proposed about thermal-mechanical fatigue crackrate in IC10 superalloy based on these experimental results. This model is composedof cycle-dependent component and time-dependent component. And two proof testswere conducted to verify this model. The results predicted by this linear summationmodel agree well with experimental data.