The Alliance for the Development of Additive Processing Technologies (ADAPT) at Colorado School of Mines announces that its scientists are part of an international research team that developed a new nickel-titanium elastocaloric cooling alloy 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.
Processing by laser powder bed fusion (L-PBF) creates fatigue-resistant nanocomposite microstructures that can cycle a million times with consistent cooling capacity. This opens the door to using AM to fabricate metal parts with shape memory characteristics and geometries that are far more complex than those made with conventional NiTi alloys.
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.
The i 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.
“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.
