Anti-phase boundary
The antiphase boundary is a planar lattice defect in ordered intermetallic phases where the regular sequence of atomic species is shifted by a lattice vector. It hinders the further gliding of dislocations and increases the high-temperature strength.
Physico-chemical mechanism of action
The antiphase boundary is a planar structure in metal alloys where two different crystal phases or lattice structures meet. At this boundary, the atomic spacings and sequences are different, leading to a lattice shift.
Metallurgical relevance & risks when welding
The antiphase boundary can impede the further gliding of dislocations in the material. This increases high-temperature strength and can lead to increased stress concentrations, which can cause cracks or hot cracks at high temperatures. With incorrect welding treatment, the antiphase boundary can enlarge or change its position, affecting the microstructure and mechanical properties.
Workshop practice & instructions
To minimize the effects of antiphase boundaries when welding, careful pretreatment of the material is important. This includes proper cleaning and removal of surface defects. When selecting the welding process and filler materials, attention should be paid to the specific properties and microstructure of the metal. Controlled cooling is crucial to avoid the occurrence of cracks. For materials at high risk, careful post-treatment such as drawing or tempering may be required.