Re: features visible at low magnification are not "clear" at high magnification
- From: Gary G <see.signature@bottom>
- Date: Wed, 28 Dec 2005 20:40:14 -0800
On 28 Dec 2005 20:49:02 -0600, Aaron <nghy@xxxxxxxxxxx> wrote:
>Hi Gary,
>
>Doubtless you are correct. However, in this case, I get the feeling
>that the equipment to sputter coat the specimen is just as
>out-of-reach as the darkfield epi- objectives. I wonder if another
>type of coating might do the same thing, say a thin coating of paint
>or perhaps a dilute carbon balck suspension.
>
>Aaron
>
Aaron:
The coating is only a few tens of Angstroms thick.
Another type???
I don't think so. Too bad, however. The ability of the sputter coat
to adhere to and enhance morphology is quite unique and stunning. A
regular specimen w/o coating is likely to be near impossible to
evaluate. With just a thin coating, the whole scene changes. This is
a key tool in forensics analysis. In this case, forensics includes
metallurgical failure.
Alumina is a big reflector. The coating stops this and yields many LM
data points. Then, in the SEM, even more is found. After that, image
processing produces even more data...if it is there to be found. If
not coated, VPSEM EBSD can show grain anomalies that otherwise would
never be found or noticed. The challenge is to sort out what the EBSD
data says. Not always trivial.
Just for the record, one must not coat alumina with Au/Pd or other
metals to get good EBSD patterns. This will not happen. Thin C is
preferred. The other option is VPSE.
Gary Gaugler, Ph.D.
Microtechnics, Inc.
Granite Bay, CA 95746
916.791.8191
gary@microtechnics dot com
.
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