Transient liquid phase (TLP)-Bonded Hastelloy X: Understanding the Influence of Bonding Temperature on Hot Corrosion

In this paper, the effects of bonding temperature (T_b) on the microstructure and hot corrosion behavior of transient liquid phase (TLP) bonded Hastelloy X (HX) superalloy were investigated. The hot corrosion tests were conducted at 900 °C for 20 h in a corrosive environment with a composition of 45 wt.% Na₂SO₄ - 55 wt.% V₂O₅. The microstructural investigations showed the isothermal solidification was completed for the joints bonded at 1070 °C, 1110 °C, and 1160 °C after 40 min. Also, the results approved that pitting corrosion and intergranular corrosion occurred after 10 and 20 h, respectively, due to nickel, chromium, and molybdenum sulfides in the bonding area of the samples. The hot corrosion tests confirmed a better resistance of the sample bonded at 1160 °C due to a more homogeneous distribution of alloy elements and a lower amount of boride compounds in the bonding interface. On contrary, due to more unfavorable distribution of alloying elements, the sample bonded at 1070 °C was more prone to hot corrosion.