Nanocrystallization of a nickel alloy subjected to surface severe plastic deformation

=A surface severe plastic deformation (SPD) method has been applied to bulk specimens of Hastelloy C2000 (R), a nickel-based alloy. A microstructural gradient that is a function of processing conditions has been obtained and analyzed in order to discern the mechanism responsible for the observed grain refinement. Microstructural defects, such as dislocations and deformation twins, have been found to be present in the deformed surface layer. The role of these defects in the surface nanocrystallization process has been discussed. (c) 2005 Elsevier B.V. All rights reserved.