| Summary: | 碩士 === 國立成功大學 === 材料科學(工程)學系 === 86 === This study is on reinforcing AC8A aluminum matrix composite
with rapidlysolidified Al-Fe-V-Si particulate by atomization.
The experimental procedure is described as follows. First, two
sizes of particulate (37∼75um and 75∼150um)were pressed into a
preform; then, by squeeze casting process, molten AC8A aluminum
alloy was infiltrated into the preform to fabricate the
aluminummatrix composites (abbreviated as FVS1212/AC8A aluminum
alloys composite). Theproduced materials were subjected to
examination, heat treatment of aginghardening. and elevated
temperature mechenical property tests. Microstructure
examination of the composite reveals that a relationship
exists betwwen the size of FVS1212 particulate and the size of
dispersoidsinside the particulate. Inside the larger FVS1212, a
consequence of slowercooling rate, coarsened dispersoids can be
found. FVS1212 particulate is found metallurgical bounded to AC8
A aluminum alloy, and this makes a contributionto rienforcement
of the composite. From room temperature to 400C,
compressionstrength of FVS1212(37∼75um)/AC8A aluminum alloy
composite is superior to that of FVS1212(75∼150um)/AC8A
aluminum alloy and AC8A aluminum alloy. And increasing
temperature, the strength ratio (composite/matrix) also
increases.By tensile test, it also reveals that FVS1212(37∼75
um)/AC8A aluminum alloy composite with smaller size of
dispersoids, exhibits higher tensile strengthunder all
temperature. The observation of fracture of FVS1212(37∼75um)/
AC8A aluminum alloy composite reveals that the fracture path
propagates mostlyaround the FVS1212(37∼75um) particulate, and
less cutting through them.On the contrary, the fracture path is
mainly through the FVS1212(75∼150um)particulate with secondary
regional crack is along the FVS1212 particulate/matrixinterface.
The AC8A matrix of FVS1212/AC8A composite can be heat treated,
and the time for reaching the peak hardness is shorter than the
unreinforced AC8A alloy.
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