Plastic deformation of nickel single crystals at low temperatures

A study has been made of the deformation of 99.8%-nickel single crystals at temperatures from 77.3 to 1.6° K in a rate-of-straining range of 7⋅10-5 to 3.5⋅10−2sec−1. It has been shown that single crystals of nickel are characterized by an increase of τ and ϵ with a lowering of the temperature to 1.7°K, and also by the appearance of jump-like straining at helium temperatures. The change in the nature of the straining dependence is probably due to the fact that with ϵ̇∼10−2sec−1 the speed of the dislocations reaches values at which dynamic effects are manifested. Evidence of this is the sharp increase in the electrical resistance of a crystal strained to the yield point, due to point defects generated with the movement of the dislocations with jogs.

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