Effect of Homogenization on the Microstructure and Magnetic Properties of Direct Laser-Deposited Magnetocaloric Ni43Co7Mn39Sn11
Effect of Homogenization on the Microstructure and Magnetic Properties of Direct Laser-Deposited Magnetocaloric Ni43Co7Mn39Sn11
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DOI：
10.1115/1.4046900
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发表时间：
2020-07-01
影响因子：
4
通讯作者：
Chmielus, Markus
中科院分区：
文献类型：
--
作者：
Stevens, Erica;Kimes, Katerina;Chmielus, Markus
将当前的冷却和制冷技术过渡到利用磁热效应的固态冷却将提高效率并消除对环境的有害影响。采用增材制造作为生产方法将增加几何自由度，并允许由磁热材料制成的热交换器中的设计通道和孔隙率，以增加用于经由流体进行热传递的表面积。这项研究是第一次证明通过直接激光沉积成功沉积Ni 43 Co 7 Mn 39 Sn 11磁热材料。样品被定义为适当或过度建造，并代表性的微观结构特征的均匀化热处理之前和之后，以及磁行为和组成相。竣工显微组织由枝晶、柱状晶粒和细长胞组成，混合有奥氏体和7 M马氏体相。均匀化增加了7 M马氏体的分数，并鼓励明显的等轴和柱状晶粒，消除枝晶和细胞状结构。弱磁性马氏体相的分数增加也导致饱和磁化强度的强烈降低。结构和性能的一些差异可能与能量密度差异有关，在适当构建的样品中导致较高的Mn损失，具有较低的粉末-能量输入比。总的来说，发现直接激光沉积（DLD）添加制造Ni-Mn基磁热材料是非常有前途的，因为在本研究中已经实现了代表性的转变、相态和磁性能。
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.