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.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/110230 |
| Date | January 1941 |
| Creators | Weaver, Bertha H. |
| Contributors | Industrial Physics |
| Publisher | Virginia Agricultural and Mechanical College and Polytechnic Institute |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis, Text |
| Format | 4 unnumbered pages, 73 leaves, 1 unnumbered leaves, application/pdf, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
| Relation | OCLC# 30407165 |
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