Phonon instabilities in a metal on the bain FCC–BCC transformation path

Abstract

In this paper, the energy of the Bain path in Al and the instability of phonons during uniaxial compression deformation along <001> are studied ab initio. It is shown that, at a strain of about 15%, dynamic loss of structure stability is observed due to short-wavelength phonons, which thus determine the theoretical strength of Al. Deformation causes shifts along the {111} planes of the initial fcc cell, leading to the formation of stacking faults. A similar formation of stacking faults was observed in [1] in the framework of simulation of compression along the <001> Ni3Al nanoparticle (L12 superstructure based on the fcc structure). The results obtained can be applied to situations in the experiment, when small defect-free regions are deformed, for example, as in nanostructured materials and during nanoindentation.