Atomistic mechanism of nucleation and growth of a face-centered orthogonal phase in small-sized single-crystalline Mo

Abstract

Phase transformation is an important deformation and blunting mechanism at the crack tip of body-centered cubic (BCC) metals. The BCC-to-face-centered orthogonal (FCO) transformation was only predicted by ab initio calculations. In this paper, the deformation behavior of the nano-sized single-crystalline Mo is in situ investigated in a high-resolution transmission electron microscope at room temperature. We uncover the strain-induced BCC-to-FCO phase transformation. The FCO Mo grows in a layer-by-layer fashion. It is a metastable phase after stress releasing, as confirmed by our ab initio calculation. The BCC-to-FCO phase transformation is realized via lattice shearing and shuffling.