Structure stability and magnetic properties of the Ni-Ru system studied by ab initio and molecular dynamics calculations together with ion beam mixing

Ab initio calculations reveal that it is energetically favorable for Ni3Ru and NiRu3 alloys to be of the D0(19) structure, while it is energetically favorable for NiRu alloy to be of the Ll(0) structure. Moreover. Ni3Ru alloys of A15 and D0(19) structures are both ferromagnetic. while NiRu alloy of the L l(2) structure can be ferromagnetic when its lattice constant is greater than 3.62, angstrom. Based oil a newly derived Ni-Ru potential, molecular dynamics simulations predict that face-centered cubic and hexagonal close packing are metastable Structures for the Ni-rich and Ru-rich alloy phases. respectively. and that under nonequilbrium conditions the Ni-Ru system may behave as if it features an isomorphous phase diagram. Interestingly. the prediction is in agreement with observations obtained from ion beam mixing of multiple metal layers. (c) 2006 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.