Irradiation of dilute Cu-W alloys with 1.8 MeV Kr+ between 300 K and 573 K is found to induce nucleation of a high density of W nano-precipitates. HRTEM and aberration-corrected STEM reveal that the ∼3 nm precipitates have a preferred orientation relationship with the matrix. A variant of the Bain relationship exists with preferred alignment occurring along Cu〈2 2 0〉|| W〈010〉, with small angular differences amongst the particles, which is compensated by interfacial dislocations or strain. The formation mechanism for such an orientation relationship is rationalized on the basis that small W clusters form within the local melt of an energetic displacements cascade, resulting in the partial alignment of the nanoprecipitates with the Cu lattice as the Cu solidifies.
Bibliographical noteFunding Information:
This work was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences , under Award # DEFG02-05ER46217 . It was carried out, in part, in the Materials Research Laboratory Central Facilities at the University of Illinois at Urbana-Champaign.