Thermal activation plasticity of nanocrystalline Ni–18.75 at. % Fe alloy in temperature range 4.2–350 K

Abstract

The mechanical properties of nanocrystalline Ni–18.75 at. % Fe alloy (average grain size ∼ 22 nm) were studied under uniaxial compression in the temperature range of 4.2–350 K. During deformation with a constant rate the temperature dependence of yield stress was registered and deformation curves were analyzed. Temperature dependences of the deforming stress, strain rate sensitivity of the deforming stress, and activation volume of plastic deformation were measured for plastic strain of 2%. Thermal activation analysis of the experimental data was carried out. It was shown that the plastic deformation in the temperature range from 35 to 350 K was controlled by a single deformation mechanism. Empirical estimates of the parameters of interaction between dislocation and local barriers were obtained and internal stress values were evaluated.