Deformed microstructures of two-phase Zr-2.5Nb alloy: Effects of the second phase hardness

Two types, A and B, of Zr-2.5Nb samples were subjected to compression tests. Both samples consisted of similar microstructure - hexagonal closed packed (hcp) alpha phase (the primary phase) and grain boundary bcc (body centered cubic) beta phase. However, the hardness of the beta phase differed between the samples respectively being hard (sample A) and soft (sample B) relative to the primary phase. This difference was caused by the presence of fine to precipitates. The relative hardness of beta phase determined almost all aspects of deformed microstructure developments. In sample A, the primary phase had higher lattice strain and in-grain misorientation developments. In sample B, on the other hand, the softer beta phase was clearly linked to more deformation twinning and associated grain size refinement and 'texturing' of the hcp a phase. (C) 2010 Elsevier B.V. All rights reserved.