| 1. |
- Jiao, Xinyang, et al.
(author)
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Effect of heating rate on porous TiAl-based intermetallics synthesized by thermal explosion
- 2017
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In: Materials and Manufacturing Processes. - : Taylor & Francis. - 1042-6914 .- 1532-2475. ; 32:5, s. 489-494
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Journal article (peer-reviewed)abstract
- TiAl-based porous materials were synthesized by a novel process of thermal explosion (TE) reaction. The effect of heating rate on expansion behavior of powder assemblies, phase compositions and pore structures were investigated. Results showed that the actual temperature of specimen increased rapidly from 655-661 °C (furnace temperature) to 1018–1136 °C (combustion temperature) in a short time interval of 25–55 s, indicating that an obvious TE reaction occurred at different heating rates (1, 2, 5 and 10°C · min−1). TE reaction in Ti/Al powder assemblies resulted in formation of open-celled TiAl-based intermetallics. When the heating rate was set at 5 °C · min−1, the maximum open porosity of 59% was obtained in Ti-Al bodies, which experienced the highest combustion temperature (1136°C) and underwent maximum volume expansion (48%). The pore size distribution was uniform and pores were interconnected in TE products.
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| 2. |
- Jiao, Xinjang, et al.
(author)
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Hierarchical porous TiAl3 intermetallics synthesized by thermal explosion with a leachable space-holder material
- 2016
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In: Materials letters (General ed.). - : Elsevier BV. - 0167-577X .- 1873-4979. ; 181, s. 261-264
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Journal article (peer-reviewed)abstract
- Porous TiAl3 intermetallics were synthesized by thermal explosion (TE) reaction with NaCl as space holder material, from Ti-75Al at.% elemental powders. Results showed that the actual temperature of specimen climbed rapidly from 667 °C to 1106 °C. As a consequence, porous TiAl3 intermetallics with high open porosity (>80%) can be easily achieved when adding NaCl particles above 50 vol%. XRD patterns showed that only single-phase TiAl3 compound was synthesized via TE. Hierarchical porous TiAl3 materials displayed three pore structures, including large pores replicating from original NaCl particles, small pores among the skeletons, and tiny pores precipitated from particle skeletons. Moreover, porous TiAl3 intermetallics exhibited a uniform pore size distribution and formed an open-cellular structures allowing for the liquid-gas separation and filtration applications
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| 3. |
- Jiao, Xinyang, et al.
(author)
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Microstructure Evolution and Pore Formation Mechanism of Porous TiAl3 Intermetallics via Reactive Sintering
- 2018
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In: Acta Metallurgica Sinica (English Letters). - : Springer. - 1006-7191 .- 2194-1289. ; 31:4, s. 440-448
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Journal article (peer-reviewed)abstract
- Porous TiAl3 intermetallics were fabricated through vacuum reactive sintering from Ti–75Al at.% elemental powder mixture. The phase compositions, expansion behaviors, pore characteristics and microstructure evolution of TiAl3 intermetallics were investigated, and the pore formation mechanism was also proposed. It was found that the actual temperature of compacts showed an acute climb from 668 to 1244 °C in 166s, while the furnace temperature maintained the linear growth of 5 °C/min, which indicated that an obvious thermal explosion (TE) reaction occurred during sintering, and only single-phase TiAl3 intermetallic was synthesized in TE products. The open porosity increased from 22.2 (green compact) to 32.8% after reactive diffusion sintering at 600 °C and rised to 58.7% after TE, then decreased to 51.2% after high-temperature homogenization at 1100 °C. Therefore, TE reaction is the dominated pore formation mechanism of porous TiAl3 intermetallics. The pore evolution in porous TiAl3 intermetallics occurred by the following mechanisms: certain intergranular pores remained among powder particles of green compact, then low-temperature sintering resulted in a further increase in porosity due to the Kirkendall effect. Moreover, TE reaction gave rise to a dramatic volume expansion because of the rapid increase in temperature, and high-temperature sintering caused densification and a slight shrinkage.
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