TEM characterization of Al/Al{sub 2}O{sub 3} composite fabricated by reactive metal infiltration
- New Mexico Inst. of Mining and Technology, Socorro, NM (United States). Dept. of Materials Engineering
- Sandia National Labs., Albuquerque, NM (United States)
The microstructure of Al/{alpha}-Al{sub 2}0{sub 3} composites made by infiltrating Al into dense mullite preforms has been characterized using transmission electron microscopy. Observations revealed that the formation of the Al/Al{sub 2}0{sub 3} composites involves three stages. Initially, Al infiltrates into a dense mullite preform through grain boundary diffusion, and reacts with mullite at grain boundaries to form a partial reaction zone. Then, a complete reaction takes place in the reaction region between the partial reaction zone and the full reaction zone to convert the dense mullite preform to a composite of {alpha}-Al{sub 2}0{sub 3} (matrix) and an Al-Si phase (thin channels). Finally, the reduced Si from the reaction diffuses out of the Al/Al{sub 2}0{sub 3} composite through the metal channels, whereas Al from the molten Al pool is continuously drawn to the reaction region until the mullite preform is consumed or the sample is removed from the molten Al pool. Based on the observed microstructure, infiltration mechanisms have been discussed, and a growth model of the composites is proposed in which the process involves repeated nucleation of Al{sub 2}0{sub 3} grains and grain growth.
- Research Organization:
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); New Mexico Inst. of Mining and Technology, Socorro, NM (United States). Dept. of Materials Engineering
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC04-94AL85000; AC04-76DP00789
- OSTI ID:
- 29452
- Report Number(s):
- SAND-95-0468C; CONF-941144-85; ON: DE95008508
- Resource Relation:
- Conference: Fall meeting of the Materials Research Society (MRS), Boston, MA (United States), 28 Nov - 9 Dec 1994; Other Information: PBD: [1994]
- Country of Publication:
- United States
- Language:
- English
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