[meteorite-list] What is and isn't a Widmanstatten Pattern was Cooling rates

From: Mr EMan <mstreman53_at_meteoritecentral.com>
Date: Tue, 8 Sep 2009 18:08:53 -0700 (PDT)
Message-ID: <528744.14565.qm_at_web55202.mail.re4.yahoo.com>

I guess once again as with CCDs my education is outdated. I see that any metal compound or mixture can be called an alloy. OR it has come into such common use the distinction between mixture and compound is obsolete when talking about metals.

Elton

--- On Tue, 9/8/09, Mr EMan <mstreman53 at yahoo.com> wrote:

> From: Mr EMan <mstreman53 at yahoo.com>
> Subject: Re: [meteorite-list] What is and isn't a Widmanstatten Pattern was Cooling rates
> To: "Meteorite-list" <meteorite-list at meteoritecentral.com>, "Jeff Grossman" <jgrossman at usgs.gov>
> Date: Tuesday, September 8, 2009, 6:38 PM
> --- On Mon, 9/7/09, Jeff Grossman
> <jgrossman at usgs.gov>
> wrote:
> <<Most of the metallic minerals in iron meteorites
> are described as
> "alloys" in that they are composed of various metals
> combined together.>>?
>
> I understood the distinction was that the Fe Ni formed a
> "chemical compound" not merely a mixture like copper and tin
> to make brass but even brass can form crystalline plates so
> that may be a bad example. It was my understanding that were
> it not for the mineral structure The Fe-Ni would be called
> an alloy.? Agreed that it is frequently discussed in
> terms of alloy.
>
> <<It does not happen as the metal cools from the
> liquid state and solidifies.>>
>
> I stand corrected, 30 years is a lot of facts to keep in
> just one's head. I did recall correctly that there is a
> temperature range and below which all translocation stops.
> Seems off the top of my head it is 800?C.
>
> <<Goldstein and coworkers have shown that the process
> is controlled by the Fe-Ni-P phase diagram>>.?
>
> I have long suspected that phosphorus was a key component
> in the process--likely as a catalyst.? The
> Schreibersite seems to exist largely at the boundaries in
> thin laminae even surrounding trolite nodules.? I look
> forward to reading Goldstein's paper.
>
> Thanks again,
> Elton
> ______________________________________________
> http://www.meteoritecentral.com
> Meteorite-list mailing list
> Meteorite-list at meteoritecentral.com
> http://six.pairlist.net/mailman/listinfo/meteorite-list
>
Received on Tue 08 Sep 2009 09:08:53 PM PDT