THE RELATIONSHIP BETWEEN PHASE INTERFACIAL PROCESSES AND DIFFUSION PROCESSES AND THE ELASTOMECHANICAL BEHAVIOR OF ZIRCONIUM-NITROGEN ALLOYS

The relation between internal friction and diffusion of nitrogen in zirconium was investigated. After loading the specimen with nitrogen the peak of the damping capacity between --100 and 30 deg C was measured which is very broad and points to a mechanism influenced by many factors. In the same temperature range the shear modulus is different from that of pure zirconium. There is indeed a slight dependence of the damping peak on the up-taken nitrogen, a clear relation however was not found. After loading with gas and the following homogenizing the damping peak is largely reduced although the percentage of nitrogen does not change. Below 0.5% nitrogen it is possible nearly to suppress the damping-phenomena. Microscopic examinations show that a clear damping anomaly does not occur before the formation of a circular reaction zone caused by the taking-up of nitrogen. The results can be interpreted by assuming that states of stress between regions rich in nitrogen and those low in nitrogen are responsible for the appearance of the damping peak between -100 and 30 deg C. It is left open how much the nitrogen atoms are involved and which specified mechanism is effective. (auth)