The initiation and continuation of plastic strain in NiAl and Ni3Al single crystals were studied by anisothermal creep tests and stress relaxation tests coupled with in situ electrical resistance measurement. Anisothermal creep tests of NiAl single crystals in the so-called dislocation-free [001] orientation showed that the plastic strain was initiated at a well-defined critical temperature. In Ni3Al, the development of dislocation density during stress relaxation was monitored with in situ electrical resistance measurement. Below the yield strength peak, where the yield strength increased anomalously with temperature, the dislocation density decreased with relaxation plastic strain. Above the yield strength peak, where the yield strength of Ni3Al exhibited a normal decrease with temperature, the dislocation density increased with the relaxation plastic strain.

The Initiation and Continuation of Plastic Strain in NiAl and Ni3Al Studied by Anisothermal Creep and Stress Relaxation Experiments. Sun, Y.Q., Yang, N.: Intermetallics, 2001, 9[10-11], 979-85