1. Solid-state diffusion welding (SD)

Solid-phase bonding is based on diffusion and local viscoplastic deformation at interface asperities. Both mechanisms are activated by temperature and contact pressure:

• the temperature for diffusion bonding is generally between 0.6 and 0.9 T _f where T _f (in K) is the lower melting temperature of the two materials;

• the stress is between 0.2 and 0.9 times σ _e , the lower of the flow stresses of the two materials at joining temperature.

These conditions are reminiscent of those chosen for powder metallurgy. This is not surprising, since powder densification technology simultaneously assembles a very large number of particles. The variation...