Dependence of the activation energy on temperature for the relaxation peak at 0.3TM in high purity single crystalline molybdenum

G.I. ZELADA-LAMBRI; O.A. LAMBRI; J.A. GARCÍA

Santiago de Chile

Congreso; SAM/CONAMET 2006; 2006

It has been recently reported an intense relaxation peak in the 840 - 1040K region for single crystalline samples previously deformed at room temperature and annealed at temperatures above that for vacancy diffusion. The peak showed a hysteresis between the warming – cooling runs, but was not affected by a bias stress. The peak temperature, intensity and activation energy differed in the two samples measured, which were of different orientation (<110> and <149>). The peak height resulted also dependent on the degree of plastic deformation of the samples at room temperature. In this work the damping and elastic modulus of molybdenum single crystals for two different orientations, <110> and <149> has been studied by using a torsion pendulum in the 300-1273K temperature range. Single crystals were prepared from zone refined single-crystal rods of molybdenum in A.E.R.E, Harwell. The residual resistivity of the samples was about 8000. The single crystals directions were chosen to favour deformation by multiple slip, <110>, and single slip, <149>. The activation energy of the relaxation peak was studied as a function of both the temperature and orientation of the samples. Possible mechanism controlling the relaxation phenomenon is discussed.