Deformation-induced structural transformation in boron-doped Ni 76Al 24

Abstract

The paper describes the effect of cold deformation on the stability of L1 2 structured hypostoichiometric Ni 76Al 24(B) alloy. During cold rolling, the order parameter decreases with the degree of deformation. After 85% cold rolling, the material transforms to DO 22 structure from its initial L1 2 structure. The lattice parameters are measured as a = 3.567 Å and c = 7.188 Å having a c/ a ratio of ∼2.015. After annealing, the metastable structure transforms back to its original L1 2 structure. The DO 22 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 Ni 3Al.