A TiNi eutectic braze alloy in foil form is utilized to diffusion braze a powder metallurgy beta gamma alloy with a nominal composition of TiAl-4Nb-3Mn (at%). The parent material is consolidated by a two-step hot isostatic pressing process, followed by a step-cooled solution heat treatment to produce a fully lamellar microstructure with fine lamellae and limited beta phase growth at the colony boundaries. Diffusion brazing experiments are conducted under vacuum at various isothermal holding temperatures and times ranging from 1030°C for 30 minutes to 1150°C for 70 minutes. The typical microstructures and mechanical properties of the joints are characterized by SEM, EDS, and microhardness measurements. The interfacial morphology of the brazed joints changes primarily with isothermal holding temperature. Microhardness levels reduced with diffusion brazing at 1150°C for 70 minutes due to reduced volume fraction of nickel rich phases and increased volume fraction of the γ phase at the centerline of the joint. Copyright

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Keywords Diffusion brazing, Microhardness, Microstructure, Titanium aluminide
Conference Materials Science and Technology Conference and Exhibition 2013, MS and T 2013
Sawatzky, T., Seo, D.Y., Hong, J.K., & Saari, H. (2013). Microstructure and hardness properties of a diffusion brazed powder metallurgy beta gamma alloy using a tini eutectic braze foil. Presented at the Materials Science and Technology Conference and Exhibition 2013, MS and T 2013.