Strain-induced structural phase transition of a Ni lattice through dissolving Ta solute atoms - art. no. 212102

The structural phase transition of a single-crystal Ni lattice upon dissolv ing Ta solute atoms is investigated by means of molecular-dynamics simulati ons with a realistic n-body Ni-Ta potential. It is found that when the solu te concentration is within 9-19 at. % of Ta, the accumulated strain results in a martensitic phase transition, i.e., face-centered-cubic (fcc) Ni tran sforms into a face-centered-orthorhombic-(fco) like structure through shear ing, and that when the solute concentration is over 21 at. % of Ta, the Ni lattice collapses and turns into an amorphous stale. Comparatively, for the case of an initial hcp Ni lattice. the same martensitic and amorphization transitions also take place. The former hcp-fco transition, however, is mai nly through atomic rearrangement as well as readjustment of lattice paramet ers, and the resultant state is almost perfect single crystal with no shear ing bands. Besides, the above structural transitions are frequently in asso ciation with a dramatic softening in shear elastic moduli.