Sintering effects on additive manufactured Ni–Mn–Ga shape memory alloys: a microstructure and thermal analysis
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This work investigates the effects of time dependency for isothermal sintering on additive manufactured Ni–Mn–Ga magnetic shape memory alloys. Binder jetting additive manufacturing was used to produce Ni–Mn–Ga parts from pre-alloyed powders. Additive manufacturing via the binder jetting technique produces parts with intrinsic porosities, based on the morphology of the source material. The Ni–Mn–Ga parts printed in this study using the binder jetting method possessed average densities of ~ 46% before sintering. These samples were sintered at 1353 K in increments of 10 h up to 50 h. Based on this temperature and time frame, (1) microstructural evolution, (2) crystallographic phase analysis, (3) transformation behaviors, and (4) thermal–physical properties were investigated. The additive manufactured Ni–Mn–Ga samples exhibited increases in densities, from ~ 74 to ~ 83% due to solid-state diffusion mechanisms. X-ray diffraction reveals that all of the additive manufactured samples have the 5 M martensitic phase at room temperature. Reversible martensitic transformation temperatures were recorded during heating and cooling cycles through differential scanning calorimetry, which indicate austenitic phase transformations occurring slightly above ambient temperatures. Additionally, analysis of the heating and cooling cycles prescribes that the entropy and Gibb’s energies decrease over the reversible martensitic transformations as sintering time increases. It is envisioned that this study will support a more synergistic manufacturing process between binder jetting additive manufacturing and post-heat treatment processes for Ni–Mn–Ga shape memory alloys.
The authors would like to acknowledge the use of the facilities within the Center for Excellence in Materials Science and Engineering and Center for Innovation in Additive Manufacturing at Youngstown State University. MPC and DRW gratefully acknowledge the financial support provided by the Engineering Technology and Commonwealth Engineering (ETCE), Pennsylvania State University.
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Conflict of interest
The authors hereby declare, to the best of their knowledge, that all relationships and/or interests of the manuscript do not include a conflict of interest.
- 4.Lagoudas DC (2008) Shape memory alloys: modeling and engineering applications. Springer, BerlinGoogle Scholar
- 14.Liu J, Rynerson M (2003) Method for article fabrication using carbohydrate binder, US6585930 B2Google Scholar