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  • Essay / Microscopic Boundary Examination - 368

    MICROCOPIC EXAMINATION OF METALSIn this experiment, our goal is to examine the microstructure of metals. By studying the microscopic structures of metals, we determine which material is best suited for a given application. We used the most common method, the optical technique, to examine the microstructure. We used a small sample cut from the metal to examine. To be able to clearly see the structure, we first cleaned and polished the sample. We first start by polishing with #1 emery paper and a few finer grades. Be careful with large abrasive particles and their streaks. Cleaning and rotating the sample 90° during transfer can avoid these problems. The next step is polishing, but washing the sample before polishing gives a more successful result. Finally, we polished the sample on a rotating cloth coated with an effective abrasive such as Al2O3-Water suspension. We continued polishing until we got a mirror-like face. Once polishing was completed, the crystal structure of the specimen, cracks, seams, non-metallic inclusions and inhomogeneities could be revealed. Before we started engraving, we first applied the mounting process. In this step, we used a matching set of matrices. We placed our sample in the die set so that the rough side of the sample was the bottom surface and the polished side was facing up. We filled the die cavity with bakelite then transferred our die to a mounpress. The mount not only protects our sample, but also making its base flat and stable helps us while we examine the sample under the microscope. In the etching process, based on the chemical composition, energy content and orientation of the grains, we determine the grain boundaries and presence. of chemically different phases. To reveal these micro structural details of the polished frame, we used an etching agent like Nital to 1 %..