The deposition of aluminide and silicide coatings on {gamma}-TiAl using the halide-activated pack cementation method
- Univ. of New South Wales, Sydney, New South Wales (Australia). School of Materials Science and Engineering
The halide-activated pack cementation method (HAPC) was utilized to deposit aluminide and silicide coatings on nominally stoichiometric {gamma}-TiAl. The deposition temperature was 1,000 C and deposition times ranged from 2 to 12 hours. The growth rates of the coatings were diffusion controlled, with the rate of aluminide growth being about a factor of 2 greater than that of silicide growth. The aluminide coating was inward growing and consisted of a thick, uniform outer layer of TiAl{sub 3} and a thin inner layer of TiAl{sub 2}, with the rate-controlling step being the diffusion of aluminum from the pack into the substrate. Annealing experiments at 1,100 C showed that the interdiffusion between the aluminide coating and the {gamma}-TiAl substrate was rapid. In contrast to the aluminide coating, the silicide coating was nonuniform and porous, consisting primarily of TiSi{sub 2}, TiSi, and Ti{sub 5}Si{sub 4}, with the rate-controlling step for the coating growth believed to be the diffusion of aluminum into the {gamma}-TiAl ahead of the silicide/{gamma}-TiAl interface. The microstructural evolution of the aluminide and silicide coating structures is discussed qualitatively.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 438541
- Journal Information:
- Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science, Journal Name: Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science Journal Issue: 12 Vol. 27; ISSN 1073-5623; ISSN MMTAEB
- Country of Publication:
- United States
- Language:
- English
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