Effects of Semi-solid Isothermal Heat Treatment on Microstructures and Damping Capacities of Fly Ash Cenosphere/AZ91D Composites
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The fly ash cenosphere/AZ91D composites were successfully prepared and isothermally heat-treated at different temperatures for different time. The effects of semi-solid isothermal heat treatment on the microstructures and damping capacities of fly ash cenosphere/AZ91D composites were investigated. With the increase in isothermal temperature or holding time, the small liquid droplets within grains increased in size but decreased in quantity. The average size and shape factor of Mg2Si particles increased with the rise of isothermal temperature. The damping capacities of the composites were improved by isothermal heat treatment. At room temperature, the composites after heat treatment at 520 and 550 °C had a higher damping capacity due to interface damping when the strain amplitude was lower than about 8.8 × 10−5, and the composite after heat treatment at 580 °C had a better damping capacity because of the dislocation damping under the condition of high strain amplitude. The damping capacities of the composites increased with the rise of the test temperature, and the damping mechanisms varied depending on different test temperatures. The interface damping played an important role when the test temperature was below about 100 °C, and the dislocation damping and grain boundary damping took effect with the rise of test temperature.
KeywordsFly ash cenosphere Magnesium matrix composite Semi-solid isothermal heat treatment Microstructural evolution Damping capacity
This work was supported by the Open Fund (No. OGE201702-07) of Key Laboratory of Oil and Gas Equipment, Ministry of Education (Southwest Petroleum University), the Key Research and Development Project of Shandong Province (No. 2016GGX102041), the Natural Science Foundation of Shandong Province (No. ZR2017LEM004) and the Fundamental Research Funds for the Central Universities of China (No. 18CX02091A).
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