Auxeticity of face-centered cubic metal (001) nanoplates

Abstract

We present the results of an atomistic study on the Poisson's ratios of face-centered cubic metal (001) nanoplates under tensile loading. Here, we find that the behavior of the Poisson's ratios of metal nanoplates is strongly dependent on the characteristics of a phase transformation that takes place in their bulk counterparts as well as on the amount of compressive stress induced in the nanoplates. In addition, we discuss the effects of the nanoplate thickness and temperature on the mechanical behavior of the nanoplates. As the thickness decreases, the amount of compressive stress increases. As a result, the metal nanoplates become more auxetic. Higher temperatures cause the phase transformation to occur sooner. Thus, strongly auxetic nanoplates can be obtained by raising the temperature. In addition to investigating the effects of the thickness and temperature, we compare the behaviors of the Poisson's ratios of (001) nanoplates of six different metals. Interestingly, the behaviors of the Poisson's ratios of the metal nanoplates differ, even though their corresponding bulks have similar and positive Poisson's ratios. This is because the six metals exhibit large differences in their surface stresses as well as in the critical strains for the phase transformation. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim