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Ni-Al Intermetallics Obtained By Cold-Rolling Elemental Metal Sheets
Technical Paper
94A139
Sector:
Language:
English
Abstract
Intermetallics based on NiAl have attractive properties for high
temperature applications as potential substitutes for superalloys,
e.g., in parts for the aerospace industry. However, before reaching
the application stage, there is still need for improvement of
properties such as low temperature ductility and creep resistance
which can be obtained through novel preparation techniques. In this
respect, we present here for the first time a reaction between Ni
and Al in equiatomic amounts promoted by cold rolling.
Reactions between metallic elements of high chemical affinity
can occur in the solid state if proper mechanical treatment is
performed to initiate interdiffusion processes (e.g., by ball
milling of powders). Alternatively, the solid state reaction can be
promoted by rolling together foils of the elements.
Foils of the elements were repeatedly rolled producing a
multilayered structure. The elements are intimately intermixed to
crystallite size of the order of a few nanometers. When the
composite was heated at around 200°C a reaction occurs with
formation of NiAl3. Further heating at 450°C brings about the
formation of NiAl. The process is followed by DSC and XRD. The
final product consists of flakes of intermetallic compound with no
particles of the elements still detectable.