Deformation-induced structural transformation in boron-doped Ni76Al24

The paper describes the effect of cold deformation on the stabilit of L1(2) structured hypostoichiometric Ni76Al24(B) alloy. During cold rolly ing, the order parameter decreases with the degree of deformation. After 85% cold rolling, the material transforms to DO22 structure from its initial L1(2) structure. The lattice parameters are measured as a = 3.567 angstrom. and c = 7.188 angstrom having a c/a ratio of similar to 2.015. After annealing, the metastable structure transforms back to its original L1(2) structure. The DO22 structure can be derived from the L1(2) structure by local rearrangement of the Ni atoms as antisites. The activation energy of the reverse transformation is similar to that for the diffusion of Ni atoms in Ni3Al. (c) 2006 Elsevier Ltd. All rights reserved.