Joint formation was accompanied by the formation of two ternary Mg-Si-Ni layers, an η-layer with Ni2Si as a precipitate next to Ni, and an ω-layer next to Mg2Si. The microstructure and elemental distribution across the interfaces were determined, and the formation of new phases at the interface was investigated and related to joint properties, including shear strength and contact resistance. All rights reserved.Ĭu/Ni/Mg2Si thermoelectric bonded joints were prepared in one step by the spark plasma sintering (SPS) method using Mg and Si powders to form Mg2Si. A long‐term stability test on Mg2SiNi3/Mg2Si joint revealed minute increase in the contact resistance as well as sufficient mechanical stability, suggesting that Mg2SiNi3 is a great candidate of the electrode materials for Mg2Si. Outperforming strength (28.29 MPa) and contact resistance (63 μΩ cm²) were observed with Mg2SiNi3 at the joint bonded for 30 min. The interfaces of fabricated joints with different sintering times were monitored by electron microscopy, followed by the measurement of shear strength and the contact resistances. The electrodes were directly bonded to Mg2Si by Field Activated Pressure Assisted sintering (FAPAS) in one‐step process. In this study, we explored the candidate electrode materials (Mg2Ni and Mg2SiNi3) for Mg2Si, which is one of the cost‐effective and environmentally friendly thermoelectric materials exhibiting high zT. While the figure of merit zT of thermoelectric materials determines the maximum efficiency of thermoelectric devices, undesired side reactions causing the growing interfacial resistance or mechanical failures between thermoelectrics and metal electrodes limit the actual performance of devices. The phase component and its evolution during aging at the joint between thermoelectric materials and electrodes are of much importance to the quality and the performance of the thermoelectric devices.
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