用经典力场探索NiTi相图,The Journal of Physical Chemistry C

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用经典力场探索NiTi相图
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2016-10-26 00:00:00 , DOI: 10.1021/acs.jpcc.6b07358
Christian Kexel _{1,

2} , Alexey V. Verkhovtsev _{1,

3} , Gennady B. Sushko ₁ , Andrei V. Korol _{1,

4} , Stefan Schramm _{2,

5} , Andrey V. Solov’yov ₁

Affiliation

用于金属材料原子建模的经典力场通常被构造为匹配在实验中或从量子级计算中获得的低温特性。但是，力场可能无法系统地重现更多的基本参数，例如熔点。在这项工作中，我们提出了一种用于建模金属化合物的修正力场，该力场已在MBN Explorer软件包中实现。它可用于模拟镍钛纳米合金的成分-温度-尺寸相图的不同区域，特别侧重于评估Ni _x Ti _{1– x}（x= 0.45–0.55）系统。几乎等原子的NiTi合金由于其形状记忆特性而成为生物医学和纳米技术应用的重中之重，但有关其结构基态特性的实验和理论却不一致。呈现的力场用于预测等原子NiTi纳米合金的基态结构。我们观察到该化合物不具有形状记忆能力，因为它在奥氏体中稳定，而不在所需的马氏体结晶相中稳定。我们利用分子动力学和蒙特卡洛技术的原子方法的所有结果均与各自的从头算算和可用的实验结果相符。

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Toward the Exploration of the NiTi Phase Diagram with a Classical Force Field

Classical force fields, used for atomistic modeling of metal materials, are typically constructed to match low-temperature properties obtained in experiments or from quantum-level calculations. However, force fields can systematically fail to reproduce further fundamental parameters, such as the melting point. In this work, we present a modified force field for modeling metallic compounds, which has been implemented in the MBN Explorer software package. It is employed to simulate different regions of the composition–temperature–size phase diagram of nickel–titanium nanoalloys with particular focus on the evaluation of the melting point of Ni_xTi_1–x (x = 0.45–0.55) systems. A near-equiatomic NiTi alloy is of paramount interest for biomedical and nanotechnology applications due to its shape memory behavior, but experiments and theory are inconsistent regarding its structural ground-state properties. The presented force field is used to predict the ground-state structure of an equiatomic NiTi nanoalloy. We observe that this compound does not possess the shape memory capacity because it stabilizes in the austenite instead of the required martensite crystalline phase. All results of our atomistic approach utilizing molecular dynamics and Monte Carlo techniques are in agreement with respective ab initio calculations and the available experimental findings.

更新日期：2016-10-26

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