McCluskey, Patrick J., Kechao Xiao, John M. Gregoire, Darren Dale, and Joost J. Vlassak. 2015. “Application of in-Situ Nano-Scanning Calorimetry and X-Ray Diffraction to Characterize Ni–Ti–Hf High-Temperature Shape Memory Alloys.” Thermochimica Acta 603 (March): 53–62. doi:10.1016/j.tca.2014.07.023.
Combinatorial nanocalorimetry and synchrotron x-ray diffraction were combined to study the martensite-austenite (M-A) phase transformation behavior of Ni-Ti-Hf shape memory alloys. A thin-film library of Ni-Ti-Hf samples with a range of compositions was deposited on a parallel nano-scanning calorimeter device using sputter deposition. Crystallization of each amorphous as-deposited sample by local heating at approximately 104 K/s produced a nanoscale grain structure of austenite and martensite. Individual samples were then cycled through the M-A transformation, while the transformation enthalpy was measured by nanocalorimetry and the low- and high-temperature phase compositions were determined by x-ray diffraction. The techniques enable correlation of the observed behavior during thermal cycling with the thermodynamic and structural properties of the samples.
Funding: Air Force Office of Scientific Research under Grants FA9550-08-1-0374 and FA9550-12-1-0098, and by the Materials Research Science and Engineering Center at Harvard University. It was performed in part at the Center for Nanoscale Systems, a member of the National Nanotechnology Infrastructure Network, which is supported by the National Science Foundation under NSF Award ECS-0335765.