Solubility criterion for sequential disordering in metal-metal multilayersupon solid-state reaction

An n-body Ni-Ti potential is derived and applied in a molecular dynamics si mulation to study the maximum supersaturated solubility of the terminal sol id solutions and solid-state reaction in a Ni/Ti bilayer. It reveals that d uring interfacial reaction of the Ni/Ti bilayer the Ti lattice reaches its maximum solubility by dissolving Ni earlier than Ni does through dissolutio n of Ti, which results in a sequential disordering of first Ti and then Ni, although Ti has a higher melting point than Ni. In the Ni-Zr, Ni-Mo and Ni -Ta systems, however, the Ni lattice collapses more rapidly because it reac hes a maximum solubility earlier than its partners, which have higher melti ng points than Ni. A solubility criterion is thus relevant for all the abov e cases; the lower the maximum solid solubility the less stable is the latt ice of the metal upon solid-state reaction.