A crystal plasticity study of heterophase interface character stability of Cu/Nb bicrystals

It has recently been shown that a highly oriented microstructure develops during severe plastic rolling deformation of Cu/Nb (fcc/bcc) nanocomposites. The deformation textures significantly deviate from those expected when rolling Cu or Nb alone, and the Cu/Nb interfaces do not correspond to those with the lowest possible formation energies. Motivated by these experimental observations, we study the heterophase interface character (HIC) stability of specific Cu/Nb bicrystal configurations under rolling conditions using a finite element crystal plasticity model. In this work, the HIC stability refers to the stability of the 5-parameter character of the interface (the orientation relationship and the interface plane) under mechanical load. Specifically, we examine how slip activity and lattice reorientation are affected by the kinematic constraint imposed by the interface. Our results show that bicrystal stability is governed by the least stable crystal.