A pre-martensitic elastic anomaly in nanomaterials: elasticity of surface and interface layers

A pre-martensitic elastic anomaly inside the stability field of the austenite phase is predicted. While relaxation patterns near surfaces and interfaces are relatively insensitive to changes of pressure, an anomaly occurs as a precursor to the ferroelastic transition. The exponential relaxation pattern maintains its characteristic length but changes amplitude, like in the elastic softening of bulk materials. This effect is not related to the movement of interfaces but represents an intrinsic feature of the surface and interface layers. This effect is expected to be observable in ceramics consisting of nanomaterials with 'soft' inter-granular interfaces. The general theory and an exactly solvable model are presented and analysed numerically.