Effect of Manganese Segregation Behavior on the Wettability of the Agcu/ Feconicrmn High-Entropy Alloy System: First-Principle Calculations and Experimental Investigation

Abstract

The influence of manganese segregation in FeCoNiCrMn high entropy alloy (HEA) on the high-temperature wetting behavior of Ag-Cu filler on HEA substrate has been investigated through first-principles calculations and experimental investigation. The Mn will prefer to segregate at the surface of high entropy alloy, and exhibits the most pronounced interaction with Ag-Cu liquid droplets during the high-temperature wetting process. As the temperature in the sessile drop experiment increases from 800 °C to 900 °C, the wetting angle decreases, accompanied by an increased Mn segregation at the surface. The interface model was investigated between the Ag and HEA with Mn segregation amount of 1%, the work of adhesion ranges from 1.82 J/m2 to 2.05 J/m2. As the Mn segregation aount increases, the work of adhesion is further enhanced, indicating that Mn segregation strengthens the interfacial bonding. The segregation has effects on the electronic structure of the surface and Ag/HEA interface. Considering that Mn acts as an enriched element while Cr is identified as a reactive element, the interfacial models accounting for mutual interaction between these two elements and Ag were analyzed. Notably, Mn variation demonstrates consistently lower energy than Cr variation in all studied systems. The Mn variation systems own substantially lower energy, while the Cr variation system own higher work of adhesion improving interfacial bonding strength. The temperature effects on contact angle and wetting diameter are studied by experimental test. With the increase of wetting temperature, the final contact angle decreases from 15° to 0°, and the time to reach wetting equilibrium is reduced from 550 seconds to 250 seconds. The Energy Dispersive Spectroscopy (EDS) analysis of the wetting cross-section after high-temperature wetting reveals significant elemental segregation at the interface, characterized by a marked reduction in Mn content and a concurrent enrichment of Cr, which exhibits excellent agreement with theoretical predictions.

Keywords: First-principles, Wettability, Surface energy, Interface structure, Work of Adhesion