Anomalies in mid-high-temperature linear thermal expansion coefficient of the closed-cell aluminum foam |
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Authors: | Hong Ye Mingyang Ma Jilin Yu |
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Institution: | 1. Department of Thermal Science and Energy Engineering, University of Science and Technology of China, Hefei, 230027, China 2. Department of Modern Mechanics, University of Science and Technology of China, Hefei, 230027, China
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Abstract: | Low-density closed-cell aluminum foam is promising to be used as load-bearing and thermal insulation components. It is necessary to systematically study its thermal expansion performance. In this work, linear thermal expansion coefficient (LTEC) of the closed-cell aluminum foam of different density was measured in the temperature range of 100–500 °C. X-ray fluorescence was used to analyze elemental composition of the cell wall material. Phase transition characteristics were analyzed with X-ray diffraction and differential scanning calorimetry. LTEC of the closed-cell aluminum foam was found to be dominated by its cell wall property and independent of its density. Particularly, two anomalies were found and experimentally analyzed. Due to the release of the residual tensile stress, the LTEC declined and even exhibited negative values. After several thermal cycles, the residual stress vanished. With temperature higher than 300 °C, instantaneous LTEC showed hysteresis, which should result from the redistribution of some residual hydrogen in the Ti2Al20Ca lattice. |
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Keywords: | Aluminum foam Thermal expansionResidual stress Phase transition Hydride Hysteresis |
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