High strain rate superplasticity in a continuously recrystallized Al-6%Mg-0.3%Sc alloy
- Lawrence Livermore National Lab., CA (United States)
- Inst. of Metals Superplasticity Problems, Ufa (Russian Federation)
The superplastic properties of a cold-rolled Al-6Mg-0.3Sc alloy were studied at temperatures between 450 and 560 C and strain rates between 10{sup {minus}4} and 10{sup 0} s{sup {minus}1}. The alloy was observed to exhibit superplasticity over wide temperature (475--520 C) and strain rate ranges ({approximately} 10{sup {minus}3}--10{sup {minus}1} s{sup {minus}1}). It was found that the addition of Sc to Al-Mg alloys resulted in a uniform distribution of fine coherent Al{sub 3}Sc precipitates which effectively pinned subgrain and grain boundaries during static and dynamic recrystallization. In this paper, the microstructural evolution during superplastic deformation was systematically examined using both optical and transmission electron microscopy. Based upon this microstructural examination, a mechanism is proposed to explain the observed high strain rate superplasticity in the alloy. A model is also proposed that describes grain boundary sliding accommodated by dislocations gliding across grains containing coherent precipitates.
- Sponsoring Organization:
- Department of the Army, Washington, DC (United States); USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 616455
- Journal Information:
- Acta Materialia, Vol. 46, Issue 8; Other Information: PBD: 1 May 1998
- Country of Publication:
- United States
- Language:
- English
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