Solidification and Weldability of Gadolinium-Containing Nickel-Based Alloys

The solidification and weldability of a Gd-containing Ni-Cr-Mo alloy has been evaluated through microstructural analyses, differential thermal analysis, hot ductility testing, welding trials, and Varestraint testing. Solidification initiates with the formation of primary Ni austenite and terminates by the formation of a secondary eutectic-like constituent consisting of austenite and a phase based on the GdNi ₅ intermetallic compound. The solidification temperature range is on the order of 110 to 130°C, and although the volume fraction of terminal constituents is higher, is similar to conventional corrosion resistant Ni-based alloys. Hot ductility measurements indicate that the elevated temperature ductility is generally adequate for rolling of plate, and is commensurate with other alloys with appreciable secondary constituent levels. Autogenous electron beam and gas-tungsten arc welds and Varestraint testing indicate that hot cracking resistance and fabrication weldability are generally acceptable. The results indicate that primary and secondary processing of these unique alloys is feasible, and that further development of the alloys is warranted.