The diffusion bonding

Diffusion bonding is one bonding method performed by diffusing atoms. Through heating and pressurizing metals, but without melting the base metals, you can produce a perfectly bonded part. When we pressurize and heat material as in the figure below (1) Initial ‘point’ contacts are produced and at the same time, an oxide film is broken due to plastic deformation. As a result, the materials become like (2). When holding the same temperature and pressure, the voids shrink due to creep deformation and diffusion of atoms. At the same time, the oxide film is broken and decomposes. As a consequence, the clean metal surface is increased and the arrangement of atoms on the bonding surface becomes closed to the grain boundary like (3). As time goes by, grains grow across the bonding surface and finally like (4).

When we bond materials using a Vacuum Hot Press it is processed in a two dimensional axial pressurization which presses down on the metal surfaces. However, it is possible to bond materials using a three dimensional process with isotropic pressurization when we use HIP.

HIP Brazing/Welding