Texture evolution in two-phase Zr/Nb lamellar composites during accumulative roll bonding

We study the texture evolution and deformation mechanisms in a Zr/Nb layered composite using a combination of electron backscattered diffraction, dislocation density evolution modeling, and polycrystal plasticity simulations. Zr/Nb composites with individual layer thicknesses ranging from 1 to 4 mm one-millimeter to four-micrometers were successfully fabricated at room temperature by accumulative roll bonding. Measured texture data during rolling and stress-strain curves in compression are presented. Under severe plastic deformation, we show that the textures of each polycrystalline phase correspond to textures of severely rolled single-phase rolled Zr and Nb. A visco-plastic self-consistent (VPSC)-dislocation density based model is applied to predict the deformation textures in the individual phases. The model indicates that large-strain deformation in Zr is accommodated by prismatic, pyramidal, and anomalously basal slip, and in Nb by both {110} and {112} slip. Our findings suggest that the polycrystalline layers of four micrometers per phase are still too coarse for the bimetal interfaces to have an effect on the texture evolution.