Elasticity and Creep of Pb Single Crystals

Abstract

The rigidity modulus and Young's modulus of lead single crystals have been measured by static methods as functions of crystal orientation. The elastic parameters so obtained are in agreement with the previous values determined dynamically by Goens and Weerts. The bending-torsion effect is large for certain orientations, and its effect upon the measurement of rigidity modulus by torsion has been studied. The elastic limit for lead under longitudinal stress occurred when the resolved shear stress on the most favorably placed octahedral plane was about 2\ifmmode\times\else\texttimes\fi{}${10}^{6}$ dynes per ${\mathrm{cm}}^{2}$. Observations have been made of the transient creep under longitudinal stress. The creep strain velocity at any instant was found to be proportional to the difference between the final strain reached under that load and the strain present at the instant.