Accession Number : AD0101327

Title :   SHEAR ALONG GRAIN BOUNDARIES IN ALUMINUM BICRYSTALS,

Corporate Author : PENNSYLVANIA UNIV PHILADELPHIA SCHOOL OF METALLURGICAL ENGINEERING

Personal Author(s) : Tung, Shiu-Kang ; Maddin, R.

Report Date : 1956

Pagination or Media Count : 38

Abstract : Aluminum bicrystals 99.99% pure having a pure tilt boundary about the less than 110 greater than axis were subjected to different stresses at various temperatures. The relative boundary displacements were observed for constant stresses. The initial rate of grain boundary gliding was found to be almost linear and a plot of the logarithm of the initial rate versus the reciprocal of the absolute temperature resulted in a series of parallel straight lines. The usual rate equation r = A sub e -Q/RT was used to calculate the activation energy for grain boundary shear. It was found to increase continuously as the boundary angle increased, and approached a maximum value for the maximum angle of mis-orientation. The mechanism for grain boundary shear was considered to be a combination process involving grain boundary self-diffusion associated with grain boundary slip (stress relaxation).

Descriptors :   *ALUMINUM, *GRAIN STRUCTURES(METALLURGY), BOUNDARY LAYER, CRYSTALS, MATHEMATICAL ANALYSIS, SHEAR STRESSES.

Distribution Statement : APPROVED FOR PUBLIC RELEASE