| Summary: | 碩士 === 南台科技大學 === 機械工程系 === 93 === This study main purpose investigated the effect of mechanical properties and microstructure of the strengthens Al-Zn-Mg-Cu alloys by scandium addition, and obtained high strength aluminum alloy of the best heat treatment condition by the experiment. On the best heat treatment condition, probing into different solution temperature, different solution time, different aging temperature and different aging time differently influence the mechanical properties of alloy. The microstructures were examined using optical microscopy (OM).
In the best heat treatment condition (solution 475℃×60min. → aging 125℃×24hr.), the hardness of 7059 aluminum alloy containing 0.05% of scandium element can be improved to HRB94.5 and 7359 aluminum alloy containing 0.11% of scandium element can be improved to HRB91.2, this effects is caused scandium institute the grain size strengthening and Al3Sc dispersion.
In the compression test, the compression strength of 7059 aluminum alloy containing 0.05% of scandium is 936.3MPa, and the compression strength of the 7359 aluminum alloy containing 0.11% of scandium improves to 1384.5MPa, these because the scandium can improve yield strength of the alloy. Observe fracture surfaces of compression test with scanning electron microscope (SEM) finally.
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