FLOW MECHANISMS AND ACOUSTICAL EMISSION DURING INITIAL YIELDING IN CRYSTALS.

A broad band acoustical emission monitoring system having a sensitivity of 8 x 10 to the -15th power wattsq cm was used in an attempt to detect acoustical emission from highly perfect tubular zinc monocrystals which were deformed in the torsional mode at room temperature. Millimicroplastic bursts ranging from 10 x 10 to the -9th power to 760 x 10 to the -9th power in strain magnitude were recorded by the loading apparatus during the initial stages of yielding but no acoustical emission accompanying the bursts could be detected. This seems to suggest that the burst behavior occurring in the initial stages of yielding of zinc is controlled by low energy release mechanisms such as dislocation node diffusion. Author