EVIDENCE OF REGION-I DEFORMATION-BEHAVIOR IN 7475-AL-ALLOY

In 7475 Al alloy, strain rate sensitivity decreases as the strain rate is decreased. This is a characteristic of deformation in Region I dur ing high temperature deformation. Grain growth is limited at low strai n rates and strains (up to epsilon=1.4) and cannot be invoked as an ex planation for the existence of an apparent region I in this alloy at t est temperatures of 457 degrees C and below. The existence of a thresh old stress due to interactions of dislocations with grain boundaries, particles, ledges and hard intermetallic particles can be considered a s a possible explanation for the existence of Region I.