Bi-crystallographic lattice structure directs grain boundary motion under shear stress
نویسندگان
چکیده
Shear stress driven grain boundary (GB) migration was found to be a ubiquitous phenomenon in small grained polycrystalline materials. Here we show that the GB displacement shift complete (DSC) dislocation mechanism for GB shear coupled migration is still functioning even if the geometry orientation of the GBs deviates a few degrees from the appropriate coincidence site lattice (CSL) GBs. It means that any large angle GB can have a considerable chance to be such a "CSL-related GB" for which the shear coupled GB migration motion can happen by the GB DSC dislocation mechanism. We conclude that the CSL-DSC bi-crystallographic lattice structure in GB is the main reason that GB can migrate under shear stress.
منابع مشابه
Decay of low-angle tilt boundaries in deformed nanocrystalline materials
A theoretical model is suggested, which describes a decay of low-angle grain boundaries in deformed nanocrystalline materials (NCMs). In the framework of the model, lattice dislocations that form a low-angle boundary are under the action of the forces owing to external (applied) and internal stresses. The balance of the forces causes the critical shear stress at which a low-angle boundary decay...
متن کاملMotion of a transverse/parallel grain boundary in a block copolymer under oscillatory shear flow
A mesoscopic model of a diblock copolymer is used to study the motion of a grain boundary separating two regions of perfectly ordered lamellar structures under an oscillatory but uniform shear flow. The case considered is a grain boundary separating lamellae along the so called parallel orientation (with wavevector parallel to the velocity gradient direction) and along the transverse orientatio...
متن کاملOn grain boundary wetting during deformation
We use numerical experiments to analyze the kinetics of grain boundary wetting in polycrystalline aggregates under the influence of an external applied shear stress. Grain boundary wetting is driven by the stress concentration at the tip of the fluid front. The extent of wetting of favorably oriented grain boundaries depends on the fluid mobility number b, which is defined as the ratio of the r...
متن کاملSolute Effects on β-Sn Grain Boundary Energy and Shear Stress
The excess enthalpy and shear strain behavior of the β-Sn (101) grain boundary containing various amounts of Ag and Cu solute atoms was investigated using molecular simulation. An increase in either type of solute at the interface lowers the excess enthalpy of the grain boundary. The enthalpies of segregation for both solute types are computed as the slope of excess enthalpy of the grain bounda...
متن کاملGrain-Boundary Sliding in AZ31 Magnesium Alloys at Room Temperature to 523K
Rolled sheets of AZ31 Mg alloys were subjected to tensile testing at temperatures ranging from room temperature to 523K. The occurrence of grain-boundary sliding (GBS) at room temperature was demonstrated by the displacement of scribed lines across grain boundaries of deformed samples. Surface relief of deformed samples was measured by use of a scanning laser microscope. GBS strain was calculat...
متن کامل