Pb基Pb-Sb合金の常温時効について

抄録

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.