EBSD Investigation of the Grain Boundary Distributions in Ultrarine-Grained Cu and Cu-Zr Polycrystals Prepared by Equal-Channel Angular Pressing
Abstract
Ultrafine-grained copper and cooper-zirconium polycrystals prepared by equal-channel angular pressing following the route Be to various strain ( 1, 2, 4 and 8 passes) were investigated using electron back-scatter diffraction. Equal-channel angular pressing resulted in significant grain-size reduction.
The original course-grained structure evolved from prolate bands of cells/subgrains enclosed by lamellar nonequilibrium grain boundaries (after the first two passes) towards an equiaxed homogeneous microstructure with equilibrium grain boundaries (after 8 passes). Significant changes in the volume fraction and the character of grain boundaries were observed both in Cu and in Cu-Zr alloy.
Pronounced evolution of twin-related boundaries (Sigma 3 '' grain boundaries) with strain (number of ECAP passes) was found in Cu while only a weak increase of Sigma 3 and Sigma 9 grain boundaries was observed in Cu-Zr alloys.