Department of Mechanical System Engineering, Faculty of Engineering, Yamanashi University, Kofu, 400-8511
Al-10%Mg alloy was isothermally annealed and tensile tested in order to investigate the effect of microstructure changes on the serration of the stress-strain curve. The effects of the formation of precipitates and decrease in concentration of solute Mg atoms with aging time on the serration were discussed in detail. The following results were obtained. The critical strain for onset of the A-type serration increased with the lapse of aging time, while that of the B-type decreased. Since it has been reported that the development of a cell structure is greatly accelerated by the formation of precipitates, it is reasonable to speculate that an increasing rate of a mobile dislocation density with increasing plastic deformation may be depressed by the formation of stable or metastable precipitates in Al-Mg based alloys. This suppression of the multiplication of the mobile dislocation may be responsible for the variation in the critical strains of the A- and the B-type serrations with the aging treatment.
(Received August 24, 2000)
aluminum magnesium alloy, serration, critical strain, aging treatment, precipitation, dislocation density, plastic deformation
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