Study of Martensitic Phase Transformation in a NiTiCu Thin‐Film Shape‐Memory Alloy Using Photoelectron Emission Microscopy
Study of Martensitic Phase Transformation in a NiTiCu Thin‐Film Shape‐Memory Alloy Using Photoelectron Emission Microscopy
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DOI：
10.1002/adfm.200600611
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发表时间：
2007-01
影响因子：
19
通讯作者：
M. Cai;S. Langford;M. Wu;W. Huang;G. Xiong;T. Droubay;A. Joly;K. Beck;W. Hess;J. Dickinson
中科院分区：
文献类型：
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作者：
M. Cai;S. Langford;M. Wu;W. Huang;G. Xiong;T. Droubay;A. Joly;K. Beck;W. Hess;J. Dickinson
利用光电子发射显微镜（PEEM）研究了多晶NiTiCu薄膜形状记忆合金的热致马氏体相变。原位PEEM图像揭示了相变温度下微观结构和光电子强度的明显变化。特别地，低温马氏体相的图像比高温奥氏体相的图像更亮，因为马氏体的功函数较低。紫外光电子能谱表明，在热循环过程中，有效功函数变化约0.16 eV。原位PEEM图像还显示，在室温膜上观察到的沟槽网络在加热过程中突然消失，并在随后的冷却过程中突然重新出现。这些沟槽的特征还在于在选定的温度下使用原子力显微镜。这些观察结果的影响，在热循环过程中的相的空间分布在这种薄膜形状记忆合金进行了讨论。
Thermally induced martensitic phase transformation in a polycrystalline NiTiCu thin‐film shape‐memory alloy is probed using photoelectron emission microscopy (PEEM). In situ PEEM images reveal distinct changes in microstructure and photoemission intensity at the phase‐transition temperatures. In particular, images of the low‐temperature, martensite phase are brighter than that of the high‐temperature, austenite phase, because of the lower work function of the martensite. UV photoelectron spectroscopy shows that the effective work‐function changes by about 0.16 eV during thermal cycling. In situ PEEM images also show that the network of trenches observed on the room‐temperature film disappears suddenly during heating and reappears suddenly during subsequent cooling. These trenches are also characterized using atomic force microscopy at selected temperatures. The implications of these observations with respect to the spatial distribution of phases during thermal cycling in this thin‐film shape‐memory alloy are discussed.