Surface Phase Transitions during Martensitic Transformations of Single-Crystal Co

Abstract

The phase transitions of close-packed surfaces that accompany the martensitic transformations between the hexagonal close-packed and face-centered cubic structures of single-crystal Co are observed in real space and in real time with secondary-electron imaging. Simultaneous measurement of the bulk resistivity is used to identify the onset of the bulk transformation. The surface transitions show a broader thermal hysteresis than that of the resistivity, indicating that the martensitic transformation is initiated in the bulk and proceeds slowly to the surface.