Re: Analysis of aluminum alloy sample Aurora TX

On Feb 2, 9:33 pm, anon45...@xxxxxxxxxxxxxx wrote:
ASSESSMENT COMMENTS ON METALLURGICAL ANALYSIS AURORA, TX ALUMINUM
SAMPLE
Anonymous, PA, 2008

1.1 Introduction
In 1973, samples from a mass of aluminum were sent by John F.
Schluesser to several metallurgical labs for analysis. From the
photographs it appears to be an irregular chip-like mass approximately
3 cm x 2 cm by 1 cm. In the published documents, it is claimed to
have been received from Bill Case of Dallas, TX on June 19, 1973. Mr.
Case reportedly found it beneath 4 inches of soil in a field in Aurora
TX, lodged against a limestone rock face.
SNIP


The MUFON Acrobat .pdf data file of the Aurora data is on the web at:
http://www.mufon.com/famous_cases/Aurora%20Texas%20Crash%20Part%201%20MUFON%20Case%20File.pdf

I could not find the metallurgical assessment on the MUFON site but
did find the pdf file corresponding to the sci.engr.metallurgy
newsgroup post of Feb 2 at:
http://www.scribd.com/doc/1618203/9202-submitter-file1-Al-Intermetallic-03

What are these materials? Are they commercially available now? Were
they commercially available in 1973? How easily could they have been
processed to produce the "debris" samples reportedly found at the
"crash site"?

In the metallurgical assessment chemical compositions of the alloys
were not stated in consistent units.
The analyses from MDRL and Anastas were in atomic percent while the
Spectro-chemical analysis was in weight percent. Weight percent is
used in commercial specifications, so I will use it.

Results for the two main elements found, iron and copper can be
summarized as follows:

Lab % Iron % Copper
MDRL 9.8 -
Spectro-chemical 0.4 5.7
Anastas 1.0 -

There are three completely different samples!

First consider the MDRL 9.8% iron sample. Now, this is suspiciously
close to being exactly ten percent. An aluminum alloy containing
nominally ten weight percent iron is a "master alloy" commonly used as
a convenient way of adding iron during the production of other
aluminum alloys. Iron melts at a much higher temperature than
aluminum, so it would not be added directly in commercial production.
It's sort of like ordering a vanilla latte at a coffee shop. They will
not stir your drink with a vanilla bean - they just will add a splash
of vanilla syrup.

See Table 1 of the Key to Nonferrous Metals article on "Master Alloys
for Aluminium Alloys: Part Two:"
http://www.key-to-nonferrous.com/default.aspx?ID=CheckArticle&NM=185
A master alloy with nominally ten percent iron has both Aluminum
Association designations (H2810, H2811) and European Community
designations (CEN AM-92600, 92601). The Aluminum Association
designations are contained in a document called the Gray sheets:
http://www.aluminum.org/Content/NavigationMenu/The_Industry/Industry_Standards/graysheets.pdf
H2810 was submitted in 2005 by the EAA (European Aluminium
Association). The Aluminum Association only began the process of
standardizing master alloys back in 1973. See:
http://www.aluminum.org/Content/NavigationMenu/The_Industry/Master_Alloys/MagicArticle.pdf
Therefore it is not clear how long ago such an alloy could have been
purchased off the shelf in the US.
However it melts at a much lower temperature than pure iron and could
easily have been recast to produce a debris sample.

Second, consider the Spectro-chemical sample containing 5.7% copper.
This corresponds to a commercial alloy called 2011 (or its
predecessor, 11S). You can buy 2011 from Alcoa under the trade name of
Toolrite:
http://www.alcoa.com/gcfp/catalog/pdf/alcoa_toolrite_2011.pdf
2011alloy also contains 0.2 to 0.6% of both lead and bismuth. These
elements are added to produce particles that make this material much
easier to machine than most other aluminum alloys. Alloy 2011 was
registered in 1954, and 11S is in the 1948 Metals Handbook. Now, both
lead and bismuth are much denser than aluminum. They also are
insoluble in liquid aluminum. If you tried to remelt a 2011 alloy,
then the lead and bismuth would wind up dropping to the bottom of the
container, just like an oil and vinegar salad dressing tends to
separate. The Spectro-chemical analysis found only 0.03% lead,
consistent with remelting of a chunk of 2011 alloy.

Third, consider the Anastas sample containing 1.0% iron. The
intentional use of iron in aluminum alloys is an inexpensive way of
making stronger material for foil. This type of commercial alloy was
around before 1973. It melts at a slightly lower temperature than pure
aluminum, so it would be easy to recast to produce "debris".

If you go to the Aluminum Association and look up their wrought alloy
composition tables (the Teal Sheets) at:
http://www.aluminum.org/Content/NavigationMenu/The_Industry/Industry_Standards/Tealsheets2006.pdf
then you will find that there is a series of 8XXX alloys. See page 20
of the pdf file (or page 12 of the printed version). Alloy 8079 was
registered in 1969. It contains 0.7 to 1.3% Fe and 0.05 to 0.30% Si.
The 8079 alloy is used commercially for aluminum foil in packaging
applications.
See "Industrial Development of Non-heat Treatable Alloys"
http://www.materialsaustralia.com/Materials_Forum/Vol28/INV%206.pdf
Also see the Alcoa European mill products catalog:
http://www.alcoa.com/mill_products/catalog/pdf/specialties/en/foil_EN.pdf

There also is an older "potluck" alloy called 8112 that was registered
back in 1954. All the composition limits in this specification are
maximums, so you can make it from whatever recycled stuff you have
around, like the vegetable soup served in a diner. You are allowed to
have up to 1% silicon, or iron, or zinc.
Now, 8112 alloy is used for highly sophisticated products like license
plates. See the "US License Plate Technology overview" at:
http://www.jrwald.com/Downloads/TagWhitepaper.pdf
More specifically 8112 Aluminum has been in state purchasing documents
for license plate stock from Virginia, New Jersey, and for
Pennsylvania: http://www.dgsweb.state.pa.us/comod/Contracts/CN00014159.pdf

Pittsburgh Pete

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