Study of Martensitic Phase transformation in a NiTiCu Thin Film Shape Memory Alloy Using Photoelectron Emission Microscopy

Journal Article · Mon Jan 01 04:00:00 EST 2007 · Advanced Functional Materials, 17(1):161-167

DOI:https://doi.org/10.1002/adfm.200600611· OSTI ID:898086

Cai, Mingdong; Langford, Stephen C.; Wu, Maggie J.; Huang, W. M.; Xiong, Gang; Droubay, Timothy C.; Joly, Alan G.; Beck, Kenneth; Hess, Wayne P.; Dickinson, J. T.

The thermally-induced martensitic phase transformation in a polycrystalline NiTiCu thin film shape memory alloy was probed by 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, due to the relatively lower work function of the martensite. Ultra-violet 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 disappear suddenly during heating and reappear suddenly during subsequent cooling. These trenches are also characterized by atomic force microscopy at selected temperatures. We describe implications of these observations with respect to the spatial distribution of phases during thermal cycling in this thin film shape memory alloy.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 898086
• Report Number(s): PNNL-SA-49610; 10196; 6292a; 6292; KC0301020
• Journal Information: Advanced Functional Materials, 17(1):161-167, Journal Name: Advanced Functional Materials, 17(1):161-167
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
COPPER ALLOYS
Environmental Molecular Sciences Laboratory
MARTENSITE
MICROSTRUCTURE
NICKEL ALLOYS
PHASE TRANSFORMATIONS
THERMAL CYCLING
THIN FILMS
TITANIUM ALLOYS
TRANSITION TEMPERATURE
WORK FUNCTIONS