Synthesis of bulk nanostructured DO 22 superlattice of Ni 3 (Mo, Nb) with high strength, high ductility, and high thermal stability

Abstract

We show that a bulk nanostructured material combining high strength, high ductility, and high thermal stability can be synthesized in a Ni-Mo-Nb alloy with composition approaching Ni 3(Mo, Nb). By means of a simple aging treatment at 700°C, the grains of the parent face-centered cubic phase are made to transform into nanosized ordered crystals with DO 22 superlattice maintaining a size of 10-20nm after up to 100 hours of aging and corresponding room-temperature yield strength of 820MPa and tensile ductility of 35. Deformation of the superlattice is found to predominantly occur by twinning on { 111 } planes of the parent phase. It is concluded that, although the respective slip systems are suppressed, most of the twinning systems are preserved in the DO 22 superlattice enhancing the ductility. Copyright © 2012 H. M. Tawancy.