The efficacy of hetero-interfaces as sinks for point defects in Cu was characterized using local measurements of tracer-impurity, radiation-enhanced diffusion (RED). The measurements were performed as a function of irradiation temperature and Cu thickness in multilayer samples, with the results being compared to steady-state kinetic rate equations to determine sink strengths. Cu-Nb Kurdjumov-Sachs (K-S) interfaces are found to be nearly ideal sinks for point defects, whereas Cu-Ni (111) hetero-epitaxial interfaces are poor sinks; Cu-V K-S interfaces are intermediate. Quantitative analysis of the RED data also yields the defect production efficiency for freely migrating defects in Cu, which is on the order of 1% for MeV Kr irradiation.
What determines precipitate morphologies in co-precipitating alloy systems? We focus on alloys of two precipitating phases, with the fast-precipitating phase acting as heterogeneous nucleation sites for a second phase manifesting slower kinetics. Kinetic lattice Monte Carlo simulations show that the interplay between interfacial and ordering energies, plus active diffusion paths, strongly affect the selection of core-shell verses appendage morphologies. We study a FeCuMnNiSi alloy using the combination of atom probe tomography and simulations, and show that the ordering energy reduction of the MnNiSi phase heterogeneously nucleated on a pre-existing copper-rich precipitate exceeds the energy penalty of a predominantly Fe/Cu interface, leading to initial appendage, rather than core-shell, formation. Diffusion of Mn, Ni and Si around and through the Cu core towards the ordered phase results in subsequent appendage growth. We further show that in cases with higher primary precipitate interface energies and/or suppressed ordering, the coreshell morphology is favored.3
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.