Kartsev Alexey, Lega Peter V, Orlov Andrey P, Pavlov Alexander I, von Gratowski Svetlana, Koledov Victor V, Ilin Alexei S
Computing Center FEB RAS, 680063 Khabarovsk, Russia.
Bauman Moscow State Technical University, 105005 Moscow, Russia.
Nanomaterials (Basel). 2022 Mar 28;12(7):1107. doi: 10.3390/nano12071107.
Recently, Ti-Ni based intermetallic alloys with shape memory effect (SME) have attracted much attention as promising functional materials for the development of record small nanomechanical tools, such as nanotweezers, for 3D manipulation of the real nano-objects. The problem of the fundamental restrictions on the minimal size of the nanomechanical device with SME for manipulation is connected with size effects which are observed in small samples of Ti-Ni based intermetallic alloys with thermoplastic structural phase transition from austenitic high symmetrical phase to low symmetrical martensitic phase. In the present work, by combining density functional theory and molecular dynamics modelling, austenite has been shown to be more stable than martensite in nanometer-sized TiNi wafers. In this case, the temperature of the martensitic transition asymptotically decreases with a decrease in the plate thickness h, and the complete suppression of the phase transition occurs for a plate with a thickness of 2 nm, which is in qualitative agreement with the experimental data. Moreover, the theoretical values obtained indicate the potential for even greater minimization of nanomechanical devices based on SME in TiNi.
最近，具有形状记忆效应（SME）的钛镍基金属间合金作为一种有前景的功能材料备受关注，可用于开发如纳米镊子等超小纳米机械工具，以对实际纳米物体进行三维操纵。对于具有形状记忆效应的用于操纵的纳米机械装置最小尺寸的基本限制问题，与尺寸效应相关，这种尺寸效应在具有从奥氏体高对称相到低对称马氏体相的热塑性结构相变的钛镍基金属间合金小样品中被观察到。在本工作中，通过结合密度泛函理论和分子动力学模拟，已表明在纳米尺寸的TiNi薄片中奥氏体比马氏体更稳定。在这种情况下，马氏体转变温度随着板厚h的减小而渐近降低，对于厚度为2nm的板会出现相变的完全抑制，这与实验数据在定性上是一致的。此外，所获得的理论值表明基于TiNi中形状记忆效应的纳米机械装置有进一步大幅小型化的潜力。
