Investigation on wetting behavior and mechanism of AgCu-Xwt.%Ti filler metal/AlN ceramic reactive wetting system: Experiments and first-principles calculations

Abstract

Abstract The wetting behavior and mechanism of AgCu-Xwt.%Ti filler metal on AlN ceramic were investigated using experiments and first-principles calculations. The results indicate that the interfacial ideal adhesion work of wetting interface after interfacial chemical reaction is a crucial factor influencing the wettability of AgCu-Xwt.%Ti/AlN wetting system. This factor is controlled by the interfacial bonding characteristic. AgCu/AlN ceramic is a non-reactive wetting system, which has poor wettability with a contact angle of 22.9°. When 1.5 wt.% of active element [Ti] is added in AgCuTi filler metal, interfacial chemical reaction occurs, producing TiN. Therefore, the wetting interface is composed of AgCu-1.5wt.%Ti filler metal after chemical reaction and TiN (ACTi-1/TiN interface), which exhibits a large interfacial ideal adhesion work of 9.908 J/m2, leading to a small contact angle of 11.7°. When Ti content increases to 3.0 wt.%, the ionic bonding strength of wetting interface, composed by AgCu-3.0wt.%Ti filler metal after chemical reaction and TiN (ACTi-2/TiN interface), becomes stronger than that of ACTi-1/TiN interface owing to the increasing residual Ti content. Consequently, the interfacial ideal adhesion work further increases to 9.711 J/m2, and a decreasing contact angle of 8.2° is achieved. However, when Ti content reaches to 4.5 wt.%, although residual Ti content in AgCu-4.5wt.%Ti filler metal after chemical reaction (ACTi-3) is further increased, both covalent and ionic bonding strengths of ACTi-3/TiN interface are closer to those of ACTi-2/TiN interface. This leads to an almost unchanged interfacial ideal adhesion work and contact angle of 9.753 J/m2 and 8.1°, respectively.