The Influence of Precipitates and Al2O3 Particulates on the Mechanical Properties of 2014 Aluminum Matrix Composite
| Autor: | Shou-Chieh Huang, 黃守傑 |
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| Rok vydání: | 1999 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 87 This study aims at investigating the mechanical properties of 2014 Al-10 vol.% Al2O3 (11.5 μm) particulate composite at the as-cast, extruded, and the aging treatment states. The mechanical properties such as hardness, tensile strength, four-point bending strength, impact toughness, and the wear resistance were studied and the optical microscope and scanning electron microscope were used to observe the microstructures. The results show that both the aging treatment and the extrusion treatment can increase the hardness and strength of aluminum matrix composite, the effect aging treatment being greater than the extrusion process. The aging treatment results in the decrease of impact toughness. This decrease in toughness is arisen primarily from the decrease in ductility in the aging treatment. On the contrary, extrusion treatment can increase the roughness of the composite. This increase in toughness is due to the increase in strength after the extrusion treatment. The SEM photographs taken from the broken impact test specimens reveal some broken alumina particulates in both the untreated and T6-treated composites with the fraction of broken alumina being greater in the T6-treated specimens. This is because after T6 treatment the strength of the composite in increased. More and more load is applied to the alumina particles before the specimen fractures. In the process of wear, the friction coefficient of the composites is not dependent on the extrusion or precipitate hardening treatment but related to the smoothness of the test surface only. Composites with higher hardness have higher wear resistance. By adding alumina to the 2014 Al alloy, the wear resistant of composite is improved. Besides the addition of alumina to the alloy, extrusion and aging treatments can also improve the wear resistance of composite, the relative potency in wear resistance being that precipitating treatment > alumina addition > extrusion treatment. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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