Dense random packed model for amorphous Ni<inf>35</inf>Zr<inf>65</inf>: Influence of the heat of mixing

The structure of amorphous Ni35Zr65 alloy was simulated by a Dense Random Packed (DRP) model. The model was relaxed by minimizing its elastic energy through the use of a modified Keating potential that included only central forces with interatomic bonds of equal strength. The Bathia-Thornton number concentration (NC) distributions and the Warren chemical short range order parameter, αw, were deduced from the model and compared with measurements in rapidly quenched Ni35Zr65. The DRP model simulates a truly random alloy for which αw = 0. Since αw = -0.04 for the actual alloy, the fraction of NiZr nearest neighbors in the alloy exceeds that in the model. The effects of decreasing the strength of any one of the interatomic bonds (NiNi, NiZr, or ZrZr) were investigated. It was found that the bond relaxations cause a sharpening of some of the peaks in NC distributions but have no effect on the value of αw. The effect of permuting Ni and Zr atoms, so as to increase the number of NiZr nearest neighbors at the expense of NiNi and ZrZr pairs, was also investigated. It was found that these permutations improve the agreement between the calculated and the measured NC distributions and generate an αw value of -0.038. © 1985.