A low-temperature joining technology suitable for high-temperature applications developed by establishing chemical potential and supercooling gradients
We designed a composite filler beginning with becoming light elements to be the main diffusing elements and (ii) controlling the diffusion of the light elements. It was achieved by establishing chemical potential and supercooling gradients and shortening the diffusion distance. As a result, a transient liquid phase bonding (TLP) composite joint with hedgehog-like reinforcements and a ductile matrix was obtained. The room-temperature (RT) shear strength of the joint produced at 460 °C for 30 min was up to 84 MPa, and it had a strength of 30 MPa at 600 °C. The hedgehog-like” reinforcements with finer or longer whiskers can provide a better load transfer effect. The progressive phase formation around NiTi was induced by the large supercooled liquid, wherein either the fastest-solidified region or the deepest-supercooled liquid served as a barrier for metallic atoms. Consequently, the lower supercooling and higher Si chemical potential in the farther region enable Si to directionally diffused towards the NiTi. This study offered a novel filler feasible for most ceramic/metal systems with the goals of low-temperature joining and high-temperature using and controllable product distribution; and this idea can be extended to develop other systems.
危险品化学品经营许可证（带存储）