Structure formation of seams using high-entropic brazing filler metal MnCoNiCuGe5

Abstract This study presents the results of investigations on the use of the high-entropy alloy MnCoNiCuGe₅ as a promising brazing filler metal for vacuum brazing of dissimilar materials. The selection of this alloy is based on its stable two-phase structure. The study provides data on the spreading behavior of the alloy on various base materials: nickel (Ni), corrosion-resistant steel 12Х18Н10Т, and the heat-resistant nickel-based superalloy IN718.Micro X-ray spectral analysis revealed that, after spreading on nickel and 12Х18Н10Т steel, a two-phase structure forms that is similar to the original structure of the filler alloy. It consists of a nickel-based solid solution and a germanium-enriched phase. When spreading on the IN718 superalloy, in addition to these phases, a third phase crystallizes, with a germanium concentration reaching up to 21.37%. A similar three-phase structure is also formed during brazing of the IN718 superalloy to 12Х18Н10Т steel.According to local micro X-ray spectral analysis, brazing with the high-entropy filler alloy results in the formation of a three-phase joint structure, whose morphology varies depending on the materials being joined. The obtained results demonstrate the potential of using high-entropy alloys as filler metals for brazing. However, it is important to consider that the structure of the solid solution may change depending on the chemical composition of the alloying elements present in the base materials.