The shape memory behavior in 63.8Ni-Al alloy
- Inst. of Physical Metallurgy, Moscow (Russian Federation)
NiAl intermetallic compound is known to exist over the composition range of 43 to 70 at.% Ni at 1,400 C. The quenched alloys containing more than 61 at.% Ni undergo a thermoelastic martensitic transformation from the high temperature B2 structure to the low temperature L1{sub 0} structure with either ABC (3R) stacking and ABCABAC (7R) stacking. The transformation point can be as high as 500 C, depending on concentration, therefore, Ni-Al are attractive for an application as high temperature shape memory alloys. The shape memory effect associated with the L1{sub 0}-B2 transformation has been demonstrated by bending of polycrystalline Ni-Al strips at room temperature and heating above A{sub f}. However, the effect of prestrain and/or external load on recovery strain has not been studied systematically. The purpose of the present paper is to investigate the transformation and the memory behavior in Ni-Al with elevated transformation temperature. The alloy consisting 63.8 at.% Ni and balance Al was chosen due to its high M{sub s} temperature, {approximately}170 C. Structure of both B2 and L1{sub 0} phases are studied at temperatures around M{sub s}. The shape memory strains induced by cooling from T > M{sub s} under different constant loads are measured and compared with those in conventional Ni-Ti alloys.
- OSTI ID:
- 271591
- Journal Information:
- Scripta Materialia, Vol. 35, Issue 3; Other Information: PBD: 1 Aug 1996
- Country of Publication:
- United States
- Language:
- English
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