Stress Relaxation by Interstitial Atomic Diffusion in Tantalum

Abstract

In a preceding article, it was shown that the internal friction peaks observed in tantalum containing small amounts of C and O are caused by the stress-induced preferential distributions of C or O among the interstices in tantalum. In order to further elucidate this viewpoint, the relaxation strength associated with these relaxations has been determined by rigidity and stress relaxation measurements in torsion covering a wide range of temperature. When the reciprocal of relaxation strength is plotted against absolute temperature, the graph is a straight line passing through the origin. This linear relationship agrees with that predicted by theory assuming a model of stress-induced preferential distribution. The finding that the extrapolated line passes through absolute zero temperature shows that the interaction between solute atoms is negligibly small. This implies that the critical temperature for self-induced preferential distribution of solute atoms is close to absolute zero.