LOW TEMPERATURE CREEP DEFORMATION OF CRYSTALS PARTICULARLY PHENOMENA AT LIQUID HELIUM TEMPERATURES.
Final rept. for 1 Mar 60-1 Mar 65,
NORTHWESTERN UNIV EVANSTON ILL DEPT OF MATERIALS SCIENCE
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Creep behavior of cadmium and mercury were investigated in the liquid helium temperature range with emphasis on the possible mechanisms of creep. Creep was found to be temperature dependent at all temperatures of investigation down to 1.75 K, and impurities in the metals had no noticeable effects. Activation energies were determined in the range 1.75-30 K and activation volume measurements were carried out. Creep behavior in the liquid temperature range was found to differ little from the usual low temperature creep at higher temperatures. At liquid helium temperatures, however, creep did not follow low temperature theories, but correction could be made by Alefelds new rate equation for processes at low temperatures. Quantum tunneling effects on creep were found to be unimportant at temperatures above 0.04 K. Author