Dislocation internal friction and temperature dependence of yield stress in high-purity molybdenum single crystals

High purity molybdenum single crystals (residual resistivity ratio ≈ 6 · 10⁴) were studied by means of computer-controlled internal friction technique at frequencies of about 100 kHz in the temperature range 6 to 300 K. The amplitude dependences of decrement were measured within the vibrational strain amplitude 10⁻⁷ to 10⁻⁴. It was established that the temperature dependence of ultrasonic amplitude providing a constant level of reversible dislocation deformation coincides well in relative units with the temperature dependence of the critical resolved shear stress at 20 to 180 K.