日本金属学会誌

J. Japan Inst. Metals, Vol. 36, No. 12 (1972),
pp. 1159-1163

The Effect of Plastic Deformation on the Precipitation in an Al-Mg-Si Alloy

Toshiya Hirata1 and Shigeru Matsuo1

1National Research Institute for Metals, Tokyo

Abstract:

The effect of plastic deformation after quenching on the precipitation in an Al-Mg-Si alloy has been investigated by means of hardness and specific heat measurements and electron microscopy. The major results obtained are as follows:
(1) It was found that the plastic deformation after quenching accelerats the age-hardening processes at 200°C and the obtained maximum hardness is higher than in the specimen aged without plastic deformation.
(2) The intermediate β' and stable β phases are formed at lower temperatures in the plastically deformed specimen after quenching. The activation energy for the formation of the intermediate β' phase in the plastically deformed specimen was determined to be about 28 kcal/mol.
(3) The density of precipitates in the specimens aged at 200°C for 67 hr increased with the amount of strain after quenching. This was considered to be attributable to a heterogeneous nucleation on dislocations and the acceleration of diffusion in terms of the nucleation theory.
(4) The precipitate β' nucleates on subgrain boundaries in the specimen aged at 270°C for 46 hr after 25% reduction in thickness by rolling after quenching.


(Received 1972/2/12)

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