Preparation, Properties, and Applications of Lamellar Ni 3 Si

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i3Si compounds have attracted more and more attentions due to their high melting point, excellent conductivity, high strength, low density, magnificent high temperature oxidation resistance, and corrosion resistance.[1–5] Due to these excellent properties, Ni3Si compounds have the greatest potential to meet ever increasing requirements of the automobile, aeronautic, and aerospace industry. Most of the previous studies focus on the regular structures of Ni3Si. Karako¨se and Keskin studied the phase transition during the solidification process by DTA under an Ar atmosphere, and found that the microstructure and solidification behavior are closely related to the composition of Ni-Si alloys.[2] Dutra et al. studied the microstructure and mechanical behavior of in situ Ni-Ni3Si composite, and found that the refined and uniform microstructure displayed an interesting combination of relatively high strength and tensile ductility at room temperature.[6] Zhang et al. studied the influences of the directional solidification rate on the microstructures and properties of the full lamellar structures.[7] Cui et al. aimed to improve the ductility of the Ni3Si compound and

KAI CUI, ZHILONG ZHAO and WENBIN LIU are with the School of Mechanical Engineering, Northwestern Polytechnical University, 710072, Xia˜ an, P.R. China. Contact e-mails: [email protected]; [email protected]. Manuscript submitted January 17, 2020.

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investigate the relationship between solidification microstructure and the properties.[8] Wei et al. demonstrated the application of directional solidification process and electrochemical selective corrosion in the preparation of lamellar Ni3Si, and indicated that the NiNi3Si eutectic alloy was ferromagnetic below 152 K with low saturation magnetization and the lamellar template exhibited a paramagnetic-to-ferromagnetic transition at low temperatures (3–15 K).[9,10] All these studies help us to fully understand the structures and mechanical properties of Ni3Si. However, there are few reports on performance other than mechanical properties. The Ni3Si structure obtained by selective corrosion in directionally solidified Ni-Ni3Si master alloy can be used as a porous material. Its unique sandwich-like laminate structure reduces weight while increasing the real surface area. In recent years, conventional porous materials such as porous carbon and foam metal have attracted wide attention in applications of electrode materials and microwave absorbing materials.[11,12] Ni3Si has the advantage of controllability besides the characteristics of common porous materials, and can be used in various applications besides structural materials. This paper aims to provide a reference for potential applications by studying the effects of directional solidification growth rate and selective corrosion time on the properties of regular lamellar Ni3Si intermetallic compound. The lamellar Ni3Si for this study was prepared by the procedure adopted in our previous works.[9,10,13,14] Commercially purchased