Vibratory Polishing of High-Purity Metals to Improve EBSD Results - Poster

EBSD experiments evaluated the band contrast of eighteen (18) high-purity (generally >99.95%) specimens mechanically prepared using five steps (four for Ti). These specimens varied from Mg (atomic number 12) to Bi (atomic number 83) and covered the range of metallic crystal structures: body-centered cubic (6), face-centered cubic (4), hexagonal close-packed (5), diamond cubic (1) and rhombohedral/trigonal (2). The table below lists the specimens prepared using our standard methods and analyzed. Results for six of these after vibratory polishing are shown in the second table.

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Last Updated on Monday, 11 February 2013 15:06

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Specimen Preparation for Electron Backscattered Diffraction - Struers

Abstract

Although some publications have claimed that mechanical specimen preparation is inadequate for producing damage-free specimens for EBSD, this is certainly not true. Our methods have concentrated upon producing the best possible surfaces using an automated grinder-polisher with standard consumable products in a reasonable amount of time and at low cost. Furthermore, these methods are highly reproducible as demonstrated by extensive tests on many metals and alloys from aluminum to zirconium. Success depends first, and foremost, upon limiting cutting damage by using the proper blade and cutter. Next, commence grinding with the finest abrasive that will remove the cutting damage in a reasonable time and make all of the specimens in the holder co-planar. Polishing is done in counter rotation with a low holder rotational speed to keep the cloth as uniformly covered with abrasive and lubricant as possible. The grinding and polishing steps must keep the surface perfectly flat for best results. After the final polish, a general purpose etch can be applied, with the specimens in the holder, to evaluate the success of the preparation and determine what the structure is. Then, remove the etched surface by repeating the final step but with about half the required time. Preparation procedures are influenced by the crystal structure of the specimen. Face-centered cubic specimens will always exhibit more damage from each step than less ductile HCP and BCC metals and alloys.

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Specimen Preparation for Electron Backscattered Diffraction - Poster

  • Five-Step Preparation Practice for Cu and Cu Alloys
  • Four-Step Practice for Hardened Steels and Cast Irons
  • Five-Step Procedure for Ni, Ni-Cu and Ni-Fe Alloys
  • Four-Step Practice for Nickel-Based Superalloys and Ni-Cr-Fe Alloys
  • Four-Step Procedure for Refractory Metals (other than Ti, Zr and Hf)
  • Five-Step Automated Procedure for Precious Metals
  • Four-Step Procedure for Refractory Metals (other than Ti, Zr and Hf)
  • Five-Step Procedure for Cobalt and its Alloys
  • Four-Step Practice for Hardened Steels and Cast Irons

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Last Updated on Monday, 11 February 2013 15:02

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Specimen Preparation for Electron Backscattered Diffraction - Buehler

Abstract

Electron backscattered diffraction (EBSD) is performed with the scanning electron microscope (SEM) to provide a wide range of analytical data ranging from crystallographic orientation studies, to phase identification to grain size measurements. The specimen’s plane of polish is oriented at a steep angle, about 72°, to horizontal. While a diffraction pattern can be obtained in less than a second, image quality is improved by utilizing a longer scan time. Grain mapping, however, requires development of diffraction patterns at each pixel in the field and is a much slower process. The quality of the diffraction pattern, which influences the confidence of the indexing of the diffraction pattern, depends upon removal of damage in the lattice due to specimen preparation. Some researchers claim that removal of this damage can only be obtained using electrolytic polishing. This text, however, demonstrates that the use of modern mechanical preparation methods, equipment and consumables does yield excellent quality diffraction patterns without use of dangerous electrolytes and the problems associated with electropolishing. Basically, if mechanical preparation results in quality polarized light images of non-cubic crystal structure elements and alloys (e.g., Sb, Be, Hf, α-Ti, Zn, Zr), or color tint etching of cubic, or non-cubic crystal structure elements or alloys produces high-quality color images, then the surface is free of harmful residual preparation damage and EBSD patterns with high pattern quality indexes will be obtained.

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Last Updated on Monday, 11 February 2013 15:00

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Metallographic Specimen Preparation for Electron Backscattered Diffraction - Part 2

Although some publications have claimed that mecahnical specimen preparation is inadequate for producing damage-free specimens for EBSD, this is certainly not true. Our methods have concentrated upon producing the best possible surfaces using an automated grinder-polisher with standard consumable products in a reasonable amount of time and at low cost. Furthermore, these methods are highly reproducable as demonstrated by extensive tests on many metals and alloys from aluminum to zirconium.

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Metallographic Specimen Preparation for Electron Backscattered Diffraction - Part 1

Although some publications have claimed that mecahnical specimen preparation is inadequate for producing damage-free specimens for EBSD, this is certainly not true. Our methods have concentrated upon producing the best possible surfaces using an automated grinder-polisher with standard consumable products in a reasonable amount of time and at low cost. Furthermore, these methods are highly reproducable as demonstrated by extensive tests on many metals and alloys from aluminum to zirconium.

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Mechanical Specimen Preparation for EBSD - Struers

Rules for Pain-Free Preparation!

Most problems come from excessive damage created during sectioning, therefore - Cut specimens with an abrasive blade designed for metallography using adequate coolant and avoiding excessive pressure to minimize damage!

  • If the specimens are not too big, <1-inch (25-mm) in diameter, use a low-speed saw or a precision saw with the appropriate blade.
  • These blades are very thin and the damage introduced in sectioning is very low while the surface finish is excellent.

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Last Updated on Monday, 11 February 2013 14:53

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resourcesThe articles and presentations that can be down-loaded from this web site are based upon work done by GFV while employed at Bethlehem Steel (1967-1983), Carpenter Technology (1983-1996), Buehler Ltd. (1996-2009) and Struers (2009-Present) and from the authors consulting work for companies such as, Latrobe Steel, Scot Forge, etc., and from his litigation work. GFV's bylined articles appearing in various issues of the ASM Handbook series have been listed here courtesy of ASM International, Materials Park, Ohio.

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