| Summary: | 碩士 === 國立交通大學 === 材料科學(工程)研究所 === 81 === Precipitation hardening can influence the mechanical properties
of the alumina-reinforced aluminum alloy(2024) composites
fabricated by squeeze casting method. Owing to the presence of
alumina fibers, the aging behavior of alumina reinforced
aluminum alloy is different from aluminum alloy(2024) .
Therefore, the condition of heat treatment for aluminum alloy
(2024) is not satisfied to alumina-reinforced aluminum alloy
(2024) composites. In the present study, we performed
investigitions of DSC, microhardness, and observations of TEM
to realize the difference of precipitation hardening processing
of the two materials. It was found that the aging hardenign
response of the matrix alloy in metal matrix composites caused
suppression of GP zones forming. The reason is that the fiber-
matrix interface can be treated as sinks of quench-in
vacancies. In addition, the precipitates of aluminum
alloy(2024) are GP zones and S', and that of alumina-reinfoced
aluminum alloy(2024) composites is only S'. The precipitation
of S' in alumima reinforced aluminum alloy(2024) composites is
less than that of aluminum alloy(2024). The precipitation of S'
is decreaed with increasing volume fraction of alumina fibers.
Therefore, the peak hardness of the matrix of alumina-
reinforced aluminum alloy (2024) composites is lower than that
of aluminum alloy(2024).
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