Journal of the Japan Institute of Metals and Materials
Online ISSN : 1880-6880
Print ISSN : 0021-4876
ISSN-L : 0021-4876
On the Aging of Lead-rich Lead-Antimony Alloys at Room Temperature
Ryoichi Nozato
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1960 Volume 24 Issue 6 Pages 387-391

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Abstract

Metallographic examination, micro-hardness measurement, and observation of specific heat vs. temperature curve were performed for studing the aging process of lead alloys containing 1, 2 and 3 wt%Sb at room temperature. (1) The change of the metallographic structure took place with aging time (t) in two stage. The first stage was of “continuous precipitation” type, and the second stage was of “discontinuous precipitation” type. It was found that the discontinuous precipitation observed was accompanied by grain-boundary migration. (2) The increase of hardness (H) could be related with the continuous precipitation. (3) The heat of re-solution ([P]) of the stable precipitates produced at room temperature prior to testing the specific heat vs. temperature curve,was determined. [P] increased with t in a single stage. The increase of [P] could be also related with the continuous precipitation. (4) The fractional changes (f) of both H and [P] seem to be represented by Johnson-Mehl’s equation; f=1−exp(−btn), where, n is a constant independent of the alloy constitution and has the value of 2.0±0.25.

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