High Vacuum Diffusion Bonding
A thermal joining process under vacuum and pressure where atoms diffuse across interfaces to produce pore-free and stress-free joints. It is primarily used for complex aerospace components.
Diffusion welding in high vacuum means: The parts are joined under pressure and heat without melting. The atoms migrate across the clean interface and bond the materials cohesively. The vacuum is important so that no oxides or impurities disturb the bond and no pores form. You need a vacuum system for this, and the surfaces must be extremely clean and flat. Parameters like temperature, pressure, and time depend strongly on the material – you have to follow the manufacturer's specifications. It's important to cool down slowly and in a controlled manner, otherwise you'll build up stresses.