Electron backscatter diffraction

About: Electron backscatter diffraction is a research topic. Over the lifetime, 15184 publications have been published within this topic receiving 317847 citations. The topic is also known as: EBSD.

Microstructure evolution of AZ series magnesium alloys during cyclic extrusion compression

Abstract: Electron Backscatter Diffraction (EBSD), transmission electron microscopy (TEM) and optical microscopy (OM) are employed to characterize the microstructure evolution of AZ31, AZ61 and AZ91 Mg alloys during cyclic extrusion compression (CEC). The results show that CEC is an efficient grain refinement method for magnesium alloys. The most effective CEC pass is the first pass. There exists a critical CEC pass for three Mg alloys and beyond this critical pass the grain size and the homogeneity of microstructure retains almost constant. With increasing CEC passes, the fraction of low angle grain boundaries (LAGBs) tends to decrease and the average misorientation angle increases. Typical network shape structure of fine grains is obtained in the microstructure of AZ31 Mg alloy with fewer Mg17Al12 particles after CEC 7 passes. The microstructure of the different Mg alloys at the same number of passes becomes more homogeneous as Mg17Al12 particles increase from AZ31, AZ61 to AZ91. The Mg17Al12 particles promote increases of the fraction of high angle grain boundaries (HAGBs), the dislocation density, the refinement process of coarse grains at initial CEC pass, and the texture randomization and delay the formation of network shape structures.

Microstructure and Texture Evolution during Friction Stir Processing of Fully Lamellar Ti-6Al-4V

Abstract: Friction stir processing (FSP) was used to locally refine a thin surface layer of the coarse, fully lamellar microstructure of investment-cast Ti-6Al-4V. Depending on the peak temperature reached in the stir zone during processing relative to the β transus, three distinct classes of microstructures were observed. Using accepted wrought product terminology, they are equiaxed, bimodal, and lamellar, except for the case of FSP, the length scale of each was smaller by at least an order of magnitude compared to typical wrought material. The evolution of an initially strain-free fully lamellar microstructure to each of these three refined conditions was characterized with scanning electron microscopy, transmission electron microscopy and electron backscatter diffraction. The fundamental mechanisms underlying grain refinement during FSP, including both the morphological changes and the formation of high-angle grain boundaries, were discussed.

Generalization of the existing relations between microstructure and yield stress from ferrite–pearlite to high strength steels

Abstract: A series of available equations allows the yield and the tensile strength of low carbon ferrite–pearlite microstructures to be expressed as a function of the optical grain size, steel composition and interstitials in solution. Over the years, as the complexity of steel microstructures has increased, some additional terms have been added to account for precipitation and forest dislocation contributions. In theory, this opens the door for an extension of these equations to bainitic microstructures. Nevertheless, there is a series of difficulties that needs to be overcome in order to improve prediction accuracy. In the present work, different microstructures (ferrite–pearlite, bainite, quenched, and quenched and tempered) were produced and tension tested in a C–Mn–Nb steel. Optical microscopy and EBSD (Electron Back Scattered Diffraction) were applied and the results were compared as a function of the tolerance angle. Based on this work, an adaptation to Pickering's equation is proposed, including its extension to other microstructures rather than ferrite–pearlite.