Study of the Deformation Mechanisms of the Superplastic Alloy Ai–Li 2090 by Texture Analysis

Abstract

The deformation mechanisms ofa superplastic A1-Li 2090 alloy have been investigated by means of texture analysis. It has been found that both crystallographic slip (CS) and grain boundary sliding (GBS) operate in response to the applied stress over a wide range of deformation, conditions. This is in contrast to well-accepted creep models, which predict that only one mechanism should operate and that the transition from one mechanism to another is abrupt and takes place over a narrow range of deformation conditions. Additionally, according to geometric (Taylor-type) models of uniaxial deformation for CS, the (110), (111), or (001) fibers should appear when 4, 6, or 8 slip systems operate. Here, however, CS contributes to stabilize orientations belonging to the a and /3 fibers.

Symbiosis between grain boundary sliding and slip creep to obtain high-strain-rate superplasticity in aluminum alloys

“…In some occasions both types of behavior coexist in the same material as a consequence of the microstructural and texture gradients. 6,7 In such cases the main texture components in the outer and mid-layers are located at different positions within the fibers. Texture gradients that are present in the initial microstructure may lead to premature facture by cavitation at the interfaces.…”