Low-temperature Superplasticity in Nanostructured Nickel and Metal Alloys
Superplasticity — the ability of a material to sustain large plastic deformation — has been demonstrated in a number of metallic, intermetallic and ceramic systems. Conditions considered necessary for superplasticity are a stable fine-grained microstructure and a temperature higher than 0.5 T m (where T m is the melting point of the matrix). Superplastic behaviour is of industrial interest, as it forms the basis of a fabrication method that canbeused to produce components having complex shapes from materials that are hard to machine, such as metal matrix composites and intermetallics. Use of superplastic forming may become even more widespread if lower deformation temperatures can be attained. Here we present observations of low-temperature superplasticity in nanocrystalline nickel, a nanocrystalline aluminium alloy (1420-Al), and nanocrystalline nickel aluminide (Ni3Al). The nanocrystalline nickel was found to be superplastic ata temperature 470 °C below that previously attained: this corresponds to 0.36T m, the lowest normalized superplastic temperature reported for any crystalline material. The nanocrystalline Ni3Al was found to be superplastic at a temperature 450 °C below the superplastic temperature in the microcrystalline regime.
S. X. McFadden et al., "Low-temperature Superplasticity in Nanostructured Nickel and Metal Alloys," Letters to Nature, Nature Publishing Group, Apr 1999.
The definitive version is available at http://dx.doi.org/10.1038/19486
Materials Science and Engineering
Civil Research and Development Foundation
National Science Foundation (U.S.)
Keywords and Phrases
Aluminium alloys; Nickel; Superplasticity
Article - Journal
© 1999 Nature Publishing Group, All rights reserved.