Photomicrograph Database

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Artifact ID BC 0633/0770
Negative Number NS180
Magnification 400x
Etchant AH/HP, FeCl3
Photo Date 5/5/2000

Photomicrograph Description

Either beta-tin martensitic needles or mechanical twins of tin.

Alloy

high-tin bronze

Structure

Hot-worked and quenched.

Metallographic Description

View A (lengthwise segment): At first glance, this appears to be a somewhat atypical quenched high-tin martensitic structure, but further examination suggests that the "needles", which appear only on the edges, could also be mechanical twins of tin. PIXE analysis confirmed that this was a high-tin bronze. There is a great deal of broken- up alpha, both inter- and intra- granularly, within a dark, almost featureless matrix, probably of gamma. Many of the grains are outlined by alpha. View B (cross-section): same appearance. In neither view is there flattening or unidirectionality of the alpha.




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