eva, M. V. Gettinger, S. V. Starenchenko, UDC 539.376:666.24 and V. A. StarenchenkoThe creep of single-crystalline Ni 3 Ge alloys subjected to compression along the strain axis [001] has been investigated. The resulting creep curves have revealed low and high secondary-creep rates. Inverse hightemperature creep behavior has been observed.

In an experiment on the temperature variation during plastic deformation of Ni 3 Ge alloy single crystals with the [ 2 3 4] orientation of the deformation axis, a dependence of the stress jump on the applied stress is investigated. It is elucidated that under conditions of cubic slip, the dependence is linear and is similar to that observed for pure metals (the Cottrell−Stokes law). The anomalous temperature dependence of the flow stress during cubic slip is confirmed in experiments on the variation of the deformation temperature.Metal alloys are widely used in all fields of technical and scientific activity. They possess a wide spectrum of operational characteristics allowing them to be used at different temperatures and stresses. The temperature variation during deformation impact leads to the change of the material state and to the occurrence of stress jumps. It was established that the stress jumps attendant to the temperature variation depend on the stress and temperature. This dependence is well described by the linear relationship of the formThis interrelation called the Cottrell−Stokes law [1] was established for pure metals and disordered solid solutions. Whereas in pure metals and disordered solid solutions the standard behavior with temperature increase is associated with decreased mechanical characteristics, a positive temperature dependence of the flow stress [2-5] called in the literature the temperature anomaly of the mechanical properties is manifested for a number of alloys with the L1 2 superstructure. This anomalous mechanical behavior is caused by superdislocations existing in the alloys, their motion, and self-blocking [6,7]. The temperature influences on the resistance to dislocation motion in two ways. On the one hand, thermal fluctuations help the applied stress to move dislocations through obstacles, and from the other hand, they activate superdislocation self-blocking. The change of the plastic deformation carriers changes also the mechanisms of the deformation processes; therefore, the patterns of these processes can also change. In this regard, it is interesting to elucidate whether the Cottrell−Stokes law is valid for ordered alloys.It is expedient to investigate the influence of temperature variation during the deformation on the ordered alloys well studied in different aspects. The Ni 3 Ge alloy for which we performed extensive cycle of investigations [8][9][10][11][12][13][14] is among them. The study of the Ni 3 Ge single crystals with the L1 2 ordered superstructure demonstrated that the Cottrell−Stokes law was valid for samples deformed along the [001] [15] and [ 1 3 9] axes [16]. However, it is necessary to find whether this law is valid for other orientations and to elucidate conditions under which it is valid.

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