Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7971773 | Materials Science and Engineering: A | 2018 | 28 Pages |
Abstract
Al-1.96Cu-0.24Mg-0.18Ag alloy single crystal with (2¯15) plane orientation has been used to investigate the effect of external stresses (50, 100, 134, 160 and 200âMPa) on the precipitation behavior of Ω, θⲠand S precipitates. The microstructure of the aged specimens was observed by transmission electron microscopy (TEM), selected area electron diffraction (SAED) and scanning transmission electron microscopy (STEM). X-ray elemental mapping under high-angle annular dark-field (HAADF) was used to analyze the elements in the precipitates. TEM images showed that the amount and distribution of the three types of precipitates are different in specimens aged under different external stresses. Along with the SAED and STEM images, the type, amount and distribution of Ω, θⲠand S precipitates were quantitatively measured. Compared to the results on stress-free aged specimen, the amount of Ω precipitates decreases in stress aged samples, while that of the S precipitates increases, and the amount of θⲠprecipitates is constant with low value. The orienting effect of stress on Ω precipitates gets serious at 100âMPa, but it decreases at 200âMPa. The orienting effect of stress on S precipitates is quite similar to that in the case of the Ω phase. As the competition of acquiring Mg and Cu atoms between S and Ω precipitates, the orienting effect of stress on S precipitates is serious from 100 to 160âMPa. Both the orienting effect of stress on Ω and S precipitates decreased because of the inhibiting effect of dislocations at 200âMPa. The orienting effect on θⲠvariants is different from that of Ω precipitates. It is serious at 50âMPa and gets weaker at 100-200âMPa.
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Physical Sciences and Engineering
Materials Science
Materials Science (General)
Authors
Xiaobin Guo, Yunlai Deng, Xinming Zhang,