Strain rate sensitivity of flow stress under superimposition of ultrasonic oscillatory stress during plastic deformation of RbCl doped with Br − or I −

Abstract

Strain rate cycling tests were carried out under superimposition of ultrasonic oscillation during plastic deformation of RbCl single crystals doped with Br − or I −. The relation between the strain rate sensitivity λ ( = d τ / d ln ⁡ ε ˙ ) of flow stress and stress decrement Δ τ due to application of oscillation has a stair-like shape and is divided into three regions, two plateaus at low and high Δ τ and the decreasing λ region between them. The stress decrement τ p at the first bending point is considered to be the effective stress due to an impurity and the value of λ p, the difference in λ between the first and second plateau regions is also a part of λ due to an impurity. Values of τ p and λ p were measured from 77 K to room temperature. Assuming the Cottrell–Bilby relation for RbCl crystals doped with Br − or I −. The interaction energies between dislocation and Br − or I − were determined to be 0.50 or 0.58 eV in RbCl, respectively.