It was recalled that a twinned microstructure was frequently observed after a martensitic phase transition. An investigation was made here of the atomic-level processes, which were associated with twin formation in a model system, by using a many-body potential that was parametrized so as to represent Zr. Molecular dynamics simulations of the martensitic phase transition, from body-centered cubic to hexagonal close-packed, revealed the evolution of a laminated twinned microstructure. Plastic deformation also occurred, thus creating basal stacking faults. The plastic deformation was such as to cause rotation of the twins. This altered the twinning angle to give the 61.5º that was characteristic of low-energy (10▪1)hcp twins. These were thereby identified as being a cause of microscopic irreversibility in the transition.

Simulation of Martensitic Microstructural Evolution in Zirconium. U.Pinsook, G.J.Ackland: Physical Review B, 1998, 58[17], 11252-7