High-temperature thermal expansion of binary alloys of Ni with Cr, Mo and Re: a comparison with molecular dynamics simulations

Abstract

In this paper, thermal expansion studies of the fcc binary alloys (M = Cr, Mo, Re) for from ambient temperature to 900 K are reported. The results of the changes in the lattice constant and the coefficient of thermal expansion with x are compared with the recent molecular dynamics (MD) simulations of Mei, Cooper and co-workers providing the first detailed comparison of this type between experiment and theory over an extended temperature and composition range. For NiMo, good agreement is obtained between experiment and theory for the increase in with x, the decrease of with x, and the temperature variation of . For NiCr, the agreement is considered to be fair for the increase of with x, the decrease of with x, and the versus temperature data. For the NiRe alloys, the observed decrease of with x (say near 900 K) is the opposite to the MD simulation prediction of an increase of with x in this system, although the theoretical predictions at higher temperatures (say 1500 K) tend to be in line with the experimental observations at 900 K. It is argued that effects of magnetic ordering are not responsible for the observed departure from the MD simulation prediction in the NiRe system. A rule-of-mixtures equation gives a linear decrease of with x for the alloys, in qualitative agreement with the experimental results.