Suppression of θ″ formation in the SiC whisker-reinforced Al-4 wt% Cu composites
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Precipitation characteristics in a powder metallurgy (Al-4wt% Cu)-SiC whisker composite were investigated using transmission electron microscopy, differential scanning calorimetry, and macrohardness measurement. The results of macrohardness measurement show that the peak ageing is significantly retarded in the SiC whisker-reinforced Al-Cu alloys. It is shown that the suppression of θ″ formation plays an important role in the retarded age hardening. The suppression of θ″ formation is attributed to a high density of dislocations due to the difference in the thermal contraction between the whiskers and matrix. Numerical analysis was performed to estimate the misfit strain generated during cooling near the whiskers. The results indicate that a high density of dislocations should be developed by the relief of the misfit strain.
KeywordsPolymer Precipitation Microscopy Electron Microscopy Transmission Electron Microscopy
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