Metallographic Preparation of Zn-21Al-2Cu Alloy for Analysis by Electron Backscatter Diffraction (EBSD)
Abstract Samples of Zn-21Al-2Cu alloy (Zinalco) that will be heavily deformed were prepared using five different manual mechanical metallographic methods. Samples were analyzed before tensile testing using the orientation imaging microscopy-electron backscatter diffraction (OIM-EBSD) technique. The effect of type and particle size during the final polishing stages for this material were studied in order to identify a method that produces a flat, damage free surface with a roughness of about 50 nm and clean from oxide layers, thereby producing diffraction patterns with high image quality (IQ) and adequate confidence indexes (CI). Our results show that final polishing with alumina and silica, as was previously suggested by other research groups for alloys that are difficult to prepare or alloys with low melting point, are not suitable for manual metallographic preparation of this alloy. Indexes of IQ and CI can be used to evaluate methods of metallographic preparation of samples studied using the OIM-EBSD technique.
Orientation Imaging Microscopy: Sample Preparation for Heavily Drawn Copper wires
The use of Orientation Imaging Microscopy (OIM) as a microcharacterization technique has evolved into a standard analytical tool for studying deformed or processed materials [1,2]. OIM technique relies on accurate orientation data via electron backscattered pattern (EBSP) measurements to recreate the microstructure of materials. In spite of the considerable advances that have been made on this technique, it is still inadequate for use in the study of heavily deformed materials [3]. This is partly due to lack of appropriate specimen preparation methods, and partly due to the interference of the fine substructures or/and grain size with the formation of the EBSPs in such materials [3]. It is therefore important to assess the extent to which specimen preparation can improve the quality of OIM data obtained from heavily deformed materials.
Texture in hot rolled austenite and resulting transformation products
Abstract By making use of a commercially processed TRIP (transformation induced plasticity) steel it was possible to directly measure the texture of hot rolled low alloyed austenite from the traces of retained austenite (9%) remaining at room temperature. This texture was used as the basis for analysing preferred orientation of the transformation products, ferrite and bainite, in the same steel. The EBSP (electron back scattering patterns) method was employed to determine textures of the different phases. The austenite condition was shown to be partially recrystallised, having a β -fibre texture in the deformed structure and a spread from cube to Goss in the recrystallised regions The polygonal ferrite and bainite textures have many similarities but also some differences, being significantly stronger in the bainite, especially the 100〈011〉 component. A model is presented which explains quite well the transformation texture based on the orientation relationship between austenite and ferrite. Where appropriate, variant selectivity is incorporated by reference to accepted theories of phase transformations in steels. Both nucleation and growth are considered to play roles in defining transformation textures, depending on the physical processes which are involved.