Investigation of the microstructure, phase transformations and mechanical properties of Dissimillar Bonded of nickel-based superalloy to Ti-Al intermetallic alloy with high-entropy alloy interlayer using transient liquid phase (TLP) method

In this study, the Dissimilar bonding of a nickel-based superalloy (Inconel ۷۱۸) to a Ti-Al intermetallic alloy with a high-entropy alloy interlayer with a chemical composition of ۱۷Co-۲۵Cu-۲۵Ni-۲۵Mn-۸Al was studied by the transient liquid phase (TLP) method at ۱۲۱۰°C with a holding time of ۶۰ minutes. By examining the microstructure of the bonding area using an optical microscope and SEM, an isothermal solidification zone was observed on both sides of the bond. By performing EDS analysis, the predicted phases for this area were Ti۲Ni -δ, α-Ti۳Al, NiAl۳ and τ۴-AlNi۲Ti on the intermetallic compound side and the γ-Ni-based solid solution phase on the Inconel ۷۱۸ side. The reaction zone on the intermetallic compound side was with two predicted phases of alpha titanium and τ۲ phase along with MnAl۶ precipitates and the wide zone in the middle of the joint which was called the Athermally Solidified Zone and the predicted phase of TiNi along with precipitates of copper, cobalt and manganese elements. Also, a Diffusion Affected Zone was seen in the vicinity of Inconel ۷۱۸ which was called the γ nickel base solid solution phase. By examining the Vickers microhardness of the joint area, it was found that in general this area had a higher hardness compared to the base metals. On the other hand, the presence of some brittle compounds in some joint areas led to a decrease in hardness compared to other joint areas.

کلیدواژه ها:

Inconel ۷۱۸ ، Ti-Al intermetallic alloy ، high entropy alloy ، transient liquid phase (TLP) ، microstructure ، microhardness