Micro Etching and Macro Etching

What is the difference between Micro Etching and Macro Etching in context to microstructure study?
i have a link
http://www.metprep.co.uk/history6_print.html
which discuss about Micro etch and macro etch? I am especially interested in Al Alloys.
Thanks
Amit
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What is the difference between Micro Etching and Macro Etching in context to microstructure study?
i have a link
http://www.metprep.co.uk/history6_print.html
which discuss about Micro etch and macro etch? I am especially interested in Al Alloys.
Thanks
Amit
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Amit Pandey wrote:

Amit:
A typical definition is that macroetching is etching of a metal surface to accentuate gross structural details such as grain flow, segregation, porosity, or cracks for observation by the unaided eye or with a microscope at magnifications of less than 25X or 50X. Microetching is development of microstructure for observation with a microscope at higher magnifications than 25X to 50X.
Typically macroetching is done on a ground surface while microetching is done on a specimen which has been both ground and polished. Thus microetching can be done with less concentrated and aggressive chemicals than for macroetching.
Pittsburgh Pete
2007 2007 2007
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snipped-for-privacy@hotmail.com wrote:

Note that the surface must be chemically polished or electropolished, otherwise you'll be observing the surface-deformed layer from grinding and not the bulk material.
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Mark Thorson wrote:

Mark:
You are correct in pointing out that the preparation and etching must be sufficient to remove the deformed surface resulting from sectioning and grinding.
However, electropolishing or chemical polishing before etching is not required to prepare aluminium before macroetching. For example, see pages 35 and 36 of the LECO metallography guide available at:
http://www.leco.com/resources/application_note_subs/pdf/metallography/Met%20Principles%20and%20Procedures%20Catalog%20200-860.pdf
Pittsburgh Pete
2007 2007 2007
DISCLAIMER
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Mark Thorson wrote:

Mark:
You are correct in pointing out that the preparation and etching must be sufficient to remove the deformed surface resulting from sectioning and grinding.
However, electropolishing or chemical polishing before etching is not required to prepare aluminium before macroetching. For example, see pages 35 and 36 of the LECO metallography guide available at:
http://www.leco.com/resources/application_note_subs/pdf/metallography/Met%20Principles%20and%20Procedures%20Catalog%20200-860.pdf
Pittsburgh Pete
2007 2007 2007
DISCLAIMER
We do not believe what we write, and neither should you. Information furnished to you is for topical (external) use only. This information may not be worth any more than either a groundhog turd, or what you paid for it (nothing). The author may not even have been either sane or sober when he wrote it down. Do not worry, be happy.
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Dear Pete When you say ground surface does it mean without polishing/grinding?
Amit
snipped-for-privacy@hotmail.com wrote:

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