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

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 (=dτ/dln⁡ε˙) of flow stress and stress decrement Δτ due to application of oscillation has a stair-like shape and is divided into three regions, two plateaus at low and high Δτ and the decreasing λ region between them. The stress decrement τp at the first bending point is considered to be the effective stress due to an impurity and the value of λp, the difference in λ between the first and second plateau regions is also a part of λ due to an impurity. Values of τp and λp 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.