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X-ray analysis of the time-softening property of a lead tin alloy

The purpose of this thesis has been the determination of the nature and cause of time-softening property of the lead-tin alloys in the solid solution range. An alloy of 19% tin, 81% lead was chosen as exhibiting the property to a degree suitable for observation of the accompanying phenomena.

The investigation proceeded in three parts: (1) an observation of the time-softening property itself by means of series of hardness tests to determine the degree of change and the time required for its accomplishment; (2) a search for x-ray evidence of possible precipitation which might be apparent as a change in the lattice constant of the crystal; and (3) conductivity measurements as a further check on whether the solution concentration was changing.

The results accordingly may be classified under the same three headings.

The change in hardness of the lead-tin alloy under investigation is intimately related to its habit of precipitating some of the excess tin from the solid solution. Both the x-ray and the conductivity test results offer supporting evidence that precipitation does occur in conjunction with the softening effect.

Apparently also the softening effect observed in the lead-tin alloy is a definite phenomenon distinct from the “over-aging” effect in which an alloy aged at high temperature increases rapidly in hardness until a certain critical hardness is reached, after which softening sets in. / M.S.

Identiferoai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/110230
Date January 1941
CreatorsWeaver, Bertha H.
ContributorsIndustrial Physics
PublisherVirginia Agricultural and Mechanical College and Polytechnic Institute
Source SetsVirginia Tech Theses and Dissertation
LanguageEnglish
Detected LanguageEnglish
TypeThesis, Text
Format4 unnumbered pages, 73 leaves, 1 unnumbered leaves, application/pdf, application/pdf
RightsIn Copyright, http://rightsstatements.org/vocab/InC/1.0/
RelationOCLC# 30407165

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