Coherent Nanoprecipitation
The precipitation of nanoscale particles maintaining the matrix lattice continuity, generating strong lattice distortions and significant hardening by effectively blocking dislocation motion.
Coherent nanoprecipitation means: during welding or heat treatment, tiny particles precipitate in the microstructure, but they do not detach from the base matrix lattice; instead, they fit neatly into the crystal structure. That sounds harmless, but it is not – the particles strain the lattice and make the weld harder and more brittle. The result is cracks or problems during machining. When welding such materials, you have to control the heat input and cooling. Too fast cooling promotes precipitation, so let the weld cool slowly, then the microstructure has time to settle.