EFFECT OF IMPURITY BARRIERS ON LOW-TEMPERATURE ANOMALIES IN PLASTICITY PARAMETERS OF BETA-SN

Plastic deformation determined by the slip of (100)[010] screw disloca tions in single crystals of beta-Sn solid solutions with different con centrations of Cd, In, and Zn impurities is studied in the temperature range 1.6-150 K. Low-temperature anomalies of the yield stress tau(0) and activation volume gamma (kinks in the temperature dependence of t au(0)(T) and peaks on the stress dependence of the activation volume ( gamma)(tau)) are observed. The parameters of anomalies are found to be determined to a considerable extent by the concentration of impurity atoms in the alloy and by the height of the barriers formed by impurit y atoms for dislocations. The observed effects are compared with the p redictions of the theory describing the influence of impurities on the motion of dislocations through Peierls barriers of complex shape. The results of analysis of experimental data are in agreement with the as sumption concerning the two-hump shape of the lattice potential relief in the (100)[010] slip system. (C) 1998 American Institute of Physics .