PRECIPITATION HARDENING IN B2-ORDERED NiAl BY Ni2AlTiCOMPOUND
来源期刊：Acta Metallurgica Sinica2001年第5期
论文作者：M.Nemoto K.Ohishi W.H.Tian
Key words：NiAl intermetallics; Ni2AlTi; age-hardening; mechanical property; precipitate;
Abstract: Microstructural variations and correlated hardness changes in B2-ordered NiAl containing fine precipitation of Ni2AlTi have been investigated by means of transmission electron microscopy (TEM) and hardness tests. The amount of age hardening is not large as compared to the large microstructural variations during aging. TEM observations have revealed that the L21-type Ni2AlTi precipitates keep a lattice coherency with the NiAl matrix at the beginning of aging. By longer periods of aging Ni2AlTi precipitates lose their coherency and change their morphology to the globular ones surrounded by misfit dislocations. The temperature dependence of the yield strength of precipitate-containing B2-ordered NiAl was investigated by compression tests over the temperature range of 873-1273K. The fine precipitation of Ni2AlTi was found to enhance greatly the yield strength and the high-temperature strength is comparison with that of superalloy Mar-M200.``
M.Nemoto1，K.Ohishi2，W.H.Tian3
(1.Sasebo National College of Technology, Okishin 1-1, Sasebo 857-1193, Japan;
2.Department of Materials Science and Engineering, Faculty of Engineering 36, Kyushu University, Fukuoka812-81, Japan;
3.Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing100083, China)
Abstract:Microstructural variations and correlated hardness changes in B2-ordered NiAl containing fine precipitation of Ni2AlTi have been investigated by means of transmission electron microscopy (TEM) and hardness tests. The amount of age hardening is not large as compared to the large microstructural variations during aging. TEM observations have revealed that the L21-type Ni2AlTi precipitates keep a lattice coherency with the NiAl matrix at the beginning of aging. By longer periods of aging Ni2AlTi precipitates lose their coherency and change their morphology to the globular ones surrounded by misfit dislocations. The temperature dependence of the yield strength of precipitate-containing B2-ordered NiAl was investigated by compression tests over the temperature range of 873-1273K. The fine precipitation of Ni2AlTi was found to enhance greatly the yield strength and the high-temperature strength is comparison with that of superalloy Mar-M200.``
Key words:NiAl intermetallics; Ni2AlTi; age-hardening; mechanical property; precipitate;
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