Scientists from the Alliance for the Development of Additive Processing Technologies (ADAPT) at Colorado School of Mines who took part in an international research team have helped develop a nickel-titanium elastocaloric cooling shape memory alloy (SMA) that is highly efficient, eco-friendly, and easily scaled up. The alloys, in which hafnium acts as a strengthening precipitate, hold the promise of requiring only heat treatment to attain functional shape memory performance.
The international team, led by University of Maryland Professor Ichiro Takeuchi, developed the improved elastocaloric cooling material using a blend of nickel and titanium metals, fabricated by a 3D printer, that is not only potentially more efficient than current technology, but is completely “green.” Moreover, it can be quickly scaled for use in larger devices.
“The key finding of the research is that while elastocaloric materials typically used for solid-state cooling show a degradation in cooling behavior after hundreds of cycles, laser melting these metals creates fatigue-resistant nanocomposite microstructures that can cycle, with consistent cooling capacity, a million times,” said Aaron Stebner, Rowlinson Associate Professor of Mechanical Engineering and a co-author of the paper.
Materials Science and Engineering, University of Maryland
“Dr. Stebner’s expertise played a crucial role in developing understanding of the fundamental mechanism behind fatigue-resistant behavior of additively manufactured shape memory alloys. His group’s in situ synchrotron diffraction and finite element modeling capabilities gave us unique insight into the inner workings of the material,” Prof. Takeuchi said.
The work, which was published in the Nov. 29 issue of Science, is the result of a collaboration led by researchers from the University of Maryland, together with Ames Laboratory, Mines, Iowa State University, and China’s Xi’an Jiaotong University.
Photo Credit: ASM International
