Documents / Report
This synopsis was prepared by Oak Ridge National Laboratory for the All-domain Anomaly Resolution Office (AARO). It reports on an analysis of drill shavings and a small bulk piece from a metallic specimen claimed to be linked to an unidentified phenomenon over central Ohio around 1995. Chemical assays, microscopy, computed tomography and gamma spectroscopy showed a conventional near-eutectic aluminum-silicon casting alloy that had cooled slowly and gave off no radiation. The report concludes the specimen is ordinary terrestrial industrial metal with no evidence of exotic origin.
Synopsis: Analysis of a Aluminum Specimen4 matrix, needle- and block-shaped silicon, Fe/Mn-rich intermetallics, and occasional Cu/Mg-bearing precipitates. Small Pb‑rich pockets are present but scarce in both the bulk and shavings, most likely representing incidental impurities commonly seen at very low levels in industrial feedstocks and tooling. This indicates that the alloy’s chemical identity is not an artifact of machining: the bulk interior matches the chemistry and phase assemblage inferred from the shavings. Figure 2. An individual shaving on a carbon sticky tape background and SEM stub, imaged at low magnification. Machining marks and deformation are noted (20 kV, in-column electron detector). 3.3 Bulk piece and computed tomography: Slow‑cooled with connected porosity — The specimen shows microstructure consistent with cast Al–Si: thin plates and needles of Si embedded in an aluminum matrix; small particles rich in Fe and Mn; and Mg–Si–Cu precipitates. The spacing and size of these features (several hundred micrometers), together with the pattern of interconnected pores, indicate slow cooling—likely in a mold, as in a large sand or permanent‑mold casting. Fast quenching (i.e., rapid cooling) produces a much finer microstructure (tens of micrometers) that was not observed. Figure 3. Optical micrographs of the polished bulk section. Background is aluminum; darker shading shows precipitates. Machining marks Folding BRIGHT FIELD DIFFERENTIAL INTERFERENCE CONTRAST 200 𝝻𝝻m
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Report, from the aaro collection. The PDF is mirrored here; the original link is above. 10 pages are in the text index: search them above, or from the library's search.