Incompatibility Dislocation
Misfit dislocation occurs at phase boundaries due to lattice mismatch between different crystal structures. It reduces the elastic strain energy and can lead to stress buildup.
Physicochemical Mechanism of Action
Misfit dislocation occurs when different crystal structures come together in a metal. These different structures have different lattice constants and therefore cannot perfectly fit into each other. To minimize elastic strain energy, atoms at phase boundaries shift, resulting in a misfit dislocation.
Metallurgical Relevance & Risks in Welding
Misfit dislocations can lead to stress buildup, especially when they are located at phase boundaries between different phases or in heterogeneous materials. These stresses can lead to cracks and fracture, especially under mechanical loads. Additionally, the dislocation can increase corrosion susceptibility, as it provides a nucleation site for corrosive agents.
Workshop Practice & Action Guidelines
To minimize misfit dislocations, it is important to carefully set the welding parameters. This includes optimal melting time and temperature as well as controlled cooling. Use appropriate filler materials and welding processes that are compatible with the involved metals. For heterogeneous materials, it is especially important to control stress states and, if necessary, take stress relief measures.