Failure Properties of Aluminum and Aluminum Alloys under Impact Conditions.

摘要

Research under this grant was directed to two distinct tasks. First was study of the kinetics of shock-induced phase transitions in solids; second was measurement of precursor amplitudes in aluminum under carefully controlled conditions. Shock-induced stresses were measured in single crystals of KCl with shock waves propagating in , , and directions and in single crystals of BaF2 with propagation in and directions. KCl measurements give clear evidence of the initiation of transformation at the established (fcc-bcc) transformation pressure. Stress-time profiles in BaF2 with orientation have a complex structure which apparently results from interaction between the shear yielding process and phase transformation. Precursor amplitudes in aluminum are uniformly low for 1060-0 commercial aluminum, 5-9's single crystals, and single crystals doped with .01 and 0.1 atomic percent copper. Variation of heat treatment to change precipitate structure affects precursor amplitude as it does static yield stress.