A low-temperature strategy to rapidly prepare high-quality diffusion-bonded joint of dissimilar superalloys enabled by pulsed current

Abstract

Joining of dissimilar superalloys is indispensable in the field of advanced manufacture, achieving a high-quality joint while minimizing thermal damage to substrates during diffusion bonding is a critical but challenging pursuit. A low-temperature and rapid diffusion bonding strategy enabled by pulsed current was proposed to resolve this challenge. Attributed to the enhanced interfacial plastic-deformation and carbide-precipitation, pulsed current rapidly achieved a nanovoid-free and tight joint of GH3536 and GH5188 superalloys at a low temperature of 850 °C for 5 min. Meanwhile, the rapid joining process prevented the interfacial carbides from coarsening and allowed their elimination in a short-term heat-treatment. The carbide dissolution, recrystallization of highly-deformed grain and cross-interface grain growth during heat-treatment significantly enhanced the joint performance, the heat-treated joint exhibited a high ultimate strain of 25.5 % and a tensile strength comparable to the raw GH3536.

Keywords

• Superalloy
• Pulsed electric current
• Low-temperature diffusion bonding
• Heat treatment
• Mechanical properties