Superplasticity-the ability of a material to sustain large plastic deformat
ion-has been demonstrated in a number of metallic, intermetallic and cerami
c systems, Conditions considered necessary for superplasticity(1) are a sta
ble fine-grained microstructure and a temperature higher than 0.5 T-m (wher
e T-m is the melting point of the matrix). Superplastic behaviour is of ind
ustrial interest, as it forms the basis of a fabrication method that can be
used to produce components having complex shapes from materials that are h
ard to machine, such as metal matrix composites and intermetallics, Use of
superplastic forming may become even more widespread if lower deformation t
emperatures can be attained. Here we present observations of low-temperatur
e superplasticity in nanocrystalline nickel, a nanocrystalline aluminium al
loy (1420-Al), and nanocrystalline nickel aluminide (Ni3Al). The nanocrysta
lline nickel was found to be superplastic at a temperature 470 degrees C be
low that previously attained(2): this corresponds to 0.36T(m), the lowest n
ormalized superplastic temperature reported for any crystalline material. T
he nanocrystalline Ni3Al was found to be superplastic at a temperature 450
degrees C below the superplastic temperature in the microcrystalline regime
(3).