Phonons, non-linear elasticity and first-principles theory of martensitic structural transformations in metals

Abstract

Martensitic transformation (MT) is a rst-order displacive structural transformation in crystalline solids which involves breaking of symmetry, induced by cooling (quenching) or applying external stresses on the high-temperature phases [1{3]. The structures stable above and below the transformation temperature are called austenite (named after W. C. Roberts-Austen) and martensite (named after Adolf Martens), respectively. Symmetry breaking of the austenite phase is a result of diffusionless (cooperative) atomic movement and deformation in which atoms displace relative to each other without breaking the bonds and not exceeding the interatomic distance. These features distinguish an MT from other transformations. It commonly occurs in steel, shape memory alloys, many elemental metals and their alloys, and ferroelectric [4] materials. The set of materials known to undergo MT is continuously increasing. These materials are of great importance to advanced technologies ranging from medical applications to robotic structures, automotive and aerospace industries. The immense technological relevance of materials undergoing MT and interesting features associated with it make MT one of the most widely studied phenomena by metallurgists and materials scientists.