Strain and strain-rate hardening characteristics of a superplastic Al-Li-Cu-Zr alloy

Journal Article · Mon Feb 01 04:00:00 EST 1988 · Scr. Metall.; (United States)

DOI:https://doi.org/10.1016/S0036-9748(88)80348-X· OSTI ID:5002432

Ash, B A; Hamilton, C H

A number of alloys based on the composition of Al-Li-Zr have been shown to be superplastic under at least one of two different microstructural conditions: 1. fully recrystallized to a fine, stable grain size, and 2. warm- or cold-worked and unrecrystallized prior to superplastic deformation. For the latter case, static recrystallization was impaired by the presence of fine Al/sub 3/Zr particles, and dynamic recrystallization was observed to occur during superplastic deformation in which the heavily worked microstructure evolved into a fine grained fully recrystallized microstructure. This process is observed in other Al alloys as well, such as the Al-Cu-Zr alloys (Supral alloys), Al-Zn-Mg-Zr alloys, Al-Mn-Zr alloys, and Al-Mg-Mn alloys where the dynamic recrystallization has been suggested to be a continuous reaction in which recrystallization occurs by a gradual and homogeneous process during deformation rather than by the more common nucleation and growth process. Experimental observations of continuous recrystallization show development of a subgrain structure which coarsens continuously while deformation proceeds, with a concurrent increase in the misorientation angle between adjacent subgrains which ultimately approaches that of a high-angle boundary, characteristic of a fully- recrystallized microstructure. During the first 50 to 300% deformation, the microstructure evolves from the heavily worked to a fully recrystallized microstructure after which the fully recrystallized microstructure apparently exhibits the typical micro-grain superplastic characteristics. Superplasticity under continuous dynamic recrystallization is of interest both from scientific and technological standpoints since the rates at which superplastic deformation can be obtained are often higher than those for the fully recrystallized microstructures.

• Research Organization: Dept. of Mechanical and Materials Engineering, Washington State Univ., Pullman, WA (US)
• OSTI ID: 5002432
• Journal Information: Scr. Metall.; (United States), Journal Name: Scr. Metall.; (United States) Vol. 22:2; ISSN SCRMB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
360103 -- Metals & Alloys-- Mechanical Properties
ALLOYS
ALUMINIUM ALLOYS
COPPER ALLOYS
CRYSTAL STRUCTURE
DEFORMATION
GRAIN SIZE
LITHIUM ALLOYS
MECHANICAL PROPERTIES
MICROSTRUCTURE
PLASTICITY
RECRYSTALLIZATION
SIZE
STRAINS
ZIRCONIUM ALLOYS