Surface Effects on Structural Phase Transformations in Nanosized Shape Memory Alloys

Z Zhang and XD Ding and JK Deng and J Cui and J Sun and T Suzuki and K Otsuka and XB Ren, JOURNAL OF PHYSICAL CHEMISTRY C, 117, 7895-7901 (2013).

DOI: 10.1021/jp401670r

We systematically investigated the role of surface on the B2-B19 transformation of free-standing nanoparticles by classical molecular dynamics simulations. It was found that the surface of particles has a shell structure with a thickness of 2 unit cells, suppressing the B2-B19 transformation locally. Below a critical size, this surface shell leads to the reduction of the transformation latent heat and the vanishing of B2-B19 transformation. We propose a Landau-type model based on the core shell structure of particles, which reproduces well the relation between transformation temperature and particle size.Our results provide a microscopic insight into the origin of surface-induced size effect on the structural phase transformations in nanosized shape memory alloys.

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