Effect of Homogenization on the Microstructure and Magnetic Properties of Direct Laser-Deposited Magnetocaloric Ni43Co7Mn39Sn11
Abstract
Transitioning current cooling and refrigeration technologies to solid-state cooling leveraging the magnetocaloric effect would improve efficiency and eliminate a harmful influence on the environment. Employing additive manufacturing as a production method would increase geometrical freedom and allow designed channels and porosity in heat exchangers made from magnetocaloric materials, to increase surface area for heat transfer via a fluid. This study is the first to demonstrate a successful deposition of the Ni43Co7Mn39Sn11 magnetocaloric material by direct laser deposition. Samples were defined as either properly- or overbuilt, and representative ones were characterized for microstructural features before and after homogenization heat treatment, as well as magnetic behavior and constituent phases. As-built microstructures consisted of dendrites, columnar grains, and elongated cells, with a mix of both austenite and 7M martensite phases. Homogenization increased the fraction of 7M martensite, and encouraged distinct equiaxed and columnar grains, eliminating dendrites and cellular structures. The increased fraction of the weak magnetic martensitic phase also resulted in a strong reduction of the saturation magnetization. Some differences in structure and performance may be related to an energy density difference causing higher Mn loss in the properly built sample, with a lower powder-to-energy input ratio. As a whole, it is found that direct laser deposition (DLD) additive manufacturing of Ni-Mn-based magnetocaloric material is very promising, since representative transformation, phase state, and magnetic properties have been achieved in this study.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- May 06, 2020
- Source ID
- 10.1115/1.4046900
Entities
People
- Anna Wojcik
- Erica Stevens
- Jakub Toman
- Katerina Kimes
- Markus Chmielus
- Patricia Lázpita
- Volodymyr Chernenko
- Wojciech Maziarz
Organizations
- Air Force Research Laboratory
- National Science Foundation
- Office of Naval Research
- Polish Academy of Sciences
- University of Pittsburgh