The axial ising model for martensitic transformations and pseudoelasticity

A theory based on the Ising axial model for the martensitic transformation between close-packed structures in an external stress field is proposed. The quasi-spin Hamiltonian was derived for a stratified close-packed crystal which under certain limitations has the form of a Hamiltonian of the ANNNI-model wherein “the exchange integrals” are expressed in terms of the interlayer interaction potentials. The dependence of the strain on the shear stress is calculated for alloys showing the pseudoelasticity effect and it is shown that the number of steps in the deformation curve is defined by the radius of the interlayer interaction. The theory proposed is applied to the explanation of the stress-induced martensitic transformations in Cu-Al-Ni alloys.