3. Control and characterization of diffusion assemblies

Non-destructive testing of the internal health of joints is carried out using a variety of methods, including acoustic microscopy, X-ray or X-ray tomography, gammagraphy and ultrasonic testing. The choice of methods depends on the nature of the materials being joined and their geometry (thickness through which the rays or particles can pass). Ultrasonic testing requires a fine grain size to reduce background noise. At present, the spatial resolution of these methods for defect size is a fraction of a millimeter. It should be noted that standard materials for non-destructive testing are best produced by diffusion welding with planar assemblies containing calibrated defects produced by machining, possibly by electroerosion, as the level of cavity deformation is negligible during welding.

Destructive testing (fracture testing) is tricky. Uniaxial tensile loading is...