Vacancy diffusion
Vacancy diffusion is the process where atoms in a crystal lattice move into adjacent empty spots. This enables diffusion of materials and has practical significance for welding and hardness improvement.
Physicochemical Mechanism of Action
Vacancy diffusion describes how atoms in a crystal lattice move into neighboring unoccupied lattice sites. This happens through energy supply by temperature or electromagnetic fields. The movement of the atoms leads to a change in the material cohesion and so enables the diffusion of substances.
Metallurgical Relevance & Welding Risks
In welding, vacancy diffusion can help metals exchange better and improve their properties. For example, it can lead to hardness improvement or reduction of pores. However, it can also lead to unwanted phenomena like distortion or unevenness of the weld if the diffusion is not controlled.
Workshop Practice & Instructions
To use vacancy diffusion effectively in the welding shop, it is important to control the temperature and time of the welding process precisely. For hardness-improving welds, sufficient heat treatment (tempering) should be carried out to promote carbon diffusion. When using filler metals or shielding gases, vacancy diffusion can be influenced to reduce pore formation and raise the hardness of the weld.