Thickness-dependence of the B2–B19 martensitic transformation in nanoscale shape memory alloy thin films: Zero-hysteresis in 75 nm thick Ti51Ni38Cu11 thin films
Thickness-dependence of the B2–B19 martensitic transformation in nanoscale shape memory alloy thin films: Zero-hysteresis in 75 nm thick Ti51Ni38Cu11 thin films
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DOI：
10.1016/j.actamat.2011.09.037
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发表时间：
2012
期刊：
影响因子：
9.4
通讯作者：
D. König;P. J. Buenconsejo;Dario Grochla;S. Hamann;J. Pfetzing‐Micklich;A. Ludwig
中科院分区：
文献类型：
--
作者：
D. König;P. J. Buenconsejo;Dario Grochla;S. Hamann;J. Pfetzing‐Micklich;A. Ludwig
研究了薄膜厚度对Ti_（51）Ni_（38）Cu_（11）纳米薄膜B_2-B_19马氏体相变特性的影响。对于这些薄膜，观察到了意想不到的相变温度行为：Δ f和θ s最初随着薄膜厚度的减小而减小，但当厚度<100 nm时再次急剧增加。相变温度和热滞宽度分别为58 - 35°C（Af）和14 - 100 K。我们首次证明了在50 nm厚的Ti-Ni-Cu薄膜上存在可逆的B2-B19相变。此外，它示出，随着膜厚度的减小，发生在B19马氏体相的四方性的变化。这导致满足所谓的λ 2判据，导致在75 nm的膜厚下滞后消失。
The influence of film thickness on the B2–B19 martensitic transformation properties of nanoscale Ti51Ni38Cu11thin films with thicknesses ranging from 750 to 50nm is reported. For these films an unexpected behavior of the phase transformation temperatures was observed: Afand Osinitially decrease with decreasing film thickness but increase sharply again for thicknesses <100nm. The phase transformation temperatures and thermal hysteresis width range from 58 to 35°C (Af) and 14 to ∼0K, respectively. For the first time we can show that substrate-attached Ti–Ni–Cu thin films as thin as 50nm show reversible B2–B19 phase transformations. Furthermore, it is shown that with decreasing film thickness a change in the tetragonality of the B19 martensite phase occurs. This leads to fulfilling the so-called λ2criterion, causing a vanishing hysteresis for a film thickness of 75nm.