Unrevealing the wetting behavior and mechanism of AgCuTi filler on negative thermal expansion Sc₂W₃O₁₂ materials: Experiments and First-principles calculations

Improving understanding of wetting behavior and mechanism between negative thermal expansion materials and filler metals was critical for the application of negative thermal expansion materials in the aerospace, precise instrument, etc. However, there is a lack of research on the wettability of negative thermal expansion materials. In this work, we employed experimental studies and First-principles calculations to investigate the wetting behavior, interfacial microstructure, and interfacial bonding characteristic between AgCuTi filler and Sc₂W₃O₁₂ materials. The sessile drop method experiment investigated the influence of Ti content on the wettability of AgCuTi filler. When the Ti content was 4.6 wt%, the minimum contact angle of 15° was achieved. The XRD and TEM results indicated that active Ti reacted with Sc₂W₃O₁₂ to form Cu₃Ti₃O, Ti₃O₅, and Cu_0.4W_0.6 compound. Furthermore, we investigated the interfacial bonding characteristics of Sc₂W₃O₁₂ (0 1 0)/Ti (0 0 1) interface and Ti₃O₅ (0 0 1)/Ti (0 0 1) interface by First-principles calculations. According to the calculations results, the work of adhesion of Ti₃O₅/Ti interface system was higher than that of Sc₂W₃O₁₂/Ti interface system, which suggested that the formed Ti₃O₅ reaction layer was conducive to improve the wettability of AgCuTi filler on the Sc₂W₃O₁₂ materials. This work provided a new vision for the wetting mechanism between metal filler and negative thermal expansion materials, and was expected to provide guidance for the design of new material systems.