Comparisons of the behavior of (111) and (001) interphase boundaries in CuAg and CuAgAu alloys

Abstract

Monte Carlo simulation, in conjunction with the embedded atom method, has been used to model the composition and structure of semicoherent (111) interphase boundaries separating Cu-rich from Ag-rich phases in binary CuAg and ternary CuAgAu alloys. The results are compared with those obtained from previous simulations of (001) interphase boundaries in the same alloys. Whereas the (001) interface had been found to decompose into {111} microfacets with a periodicity related to the period of the misfit dislocations lying in the interface, interfaces with the (111) orientation are found to be stable. The segregation of Au in ternary CuAgAu alloys, which appears weak at the (001) interface because of the distribution of Au over the surface of the microfacets, is found to be considerably stronger at the (111) interface. Finally, the results obtained lead to the conclusion that instability of the (001) interface to faceting is driven primarily by the opportunity for interfacial energy reduction, and not by compositional interactions associated with the presence of interfacial dislocations.