Thermostability of Sm{sub 2}(FeGa){sub 17}C{ital {sub y}} prepared by gas-solid reaction (GSR)
- Institute for Solid State and Materials Research Dresden, P.O. Box 270016, D-01171 Dresden (Germany)
The gas-solid-reaction (GSR) was used to introduce interstitial carbon atoms into Sm{sub 2}Fe{ital {sub 17{minus}x}}Ga{ital {sub x}} compounds with {ital x=0}, 0.5, 1, and 2. For this process, powders made from homogenized ingots were annealed at 500{degree}C under methane for different times. The thermostability increases for small amounts of Ga and the investigation shows that Sm{sub 2}Fe{sub 16.5}Ga{sub 0.5}C{ital {sub y}} is stable up to 750{degree}C. In the case of Sm{sub 2}Fe{sub 15}Ga{sub 2}C{ital {sub y}} carburized for 6 h {ital (y=2.0)} and 18 h {ital (y=2.2)}, the x-ray diffraction patterns show the Th{sub 2}Zn{sub 17}-type structure only. After annealing at 800{degree}C for 20 min the 6 h carburized sample shows a small amount of {alpha}-Fe and other phases and there is a large Fe content after annealing at 850{degree}C. For an 18 h carburized sample, less Fe and no other phases have be seen after annealing at 800{degree}C, i.e., the material is nearly single phase. The result that longer carburization times stabilize the Th{sub 2}Zn{sub 17}-type structure could also be manifested by Kerr microscopy. A comparison with mechanically alloyed Sm{sub 2}Fe{sub 15}Ga{sub 2}C{sub 2} powders prepared with Sm excess shows that those are very stable up to 900{degree}C. The density of fine-grained Sm{sub 2}Fe{ital {sub 17{minus}x}}Ga{ital {sub x}}C{ital {sub y}} could be increased by hot pressing, but the degree of compaction and the phase purity very sensitively depend on the Ga content. {copyright} {ital 1997 American Institute of Physics.}
- OSTI ID:
- 496492
- Report Number(s):
- CONF-961141--
- Journal Information:
- Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 8 Vol. 81; ISSN JAPIAU; ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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