Browsing by Author "Liu, Tzeng Feng"

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Effect of chromium content on corrosion Behaviors of Fe-9Al-30Mn-(3,5,6.5,8)Cr-1C alloys
(2007-11-01)
Wang, Cheng Shun
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Tsai, Cheng Yao
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Chao, Chuen Guang
;
Liu, Tzeng Feng
;
材料科學與工程學系
The corrosion behaviors of the as-quenched austenitic Fe-9%Al-30%Mn-(3,5,6.5,8)%Cr-I %C (in mass%) alloys in 3.5 % NaCI solution have been examined. Passivation could be observed for all of the four alloys. The corrosion potential (E-corr) and pitting potential (E-pp) increased pronouncedly as Cr content increased from 3 to 5%, and decreased as Cr content up to 6.5 and 8%. The decrease of E-corr and Epp of alloys containing 6.5 and 8% Cr was due to the formation of (Fe,Mn,Cr)(7)C-3 carbides within the austenite matrix and on the grain boundaries. The present result indicates that the Fe-9%Al-30%Mn-5%Cr-l%C alloy exhibited the highest corrosion resistance in 3.5% NaCl solution. It is worthy to note that the corrosion behaviors of the austenitic FeAlMnCrC alloys with higher Cr (>= 3%) content have never been reported in previous literature.
Grain boundary precipitation in Fe-30Mn-9Al-5Cr-0.7C alloy
(2008-07-01)
Tuan, Yi Hsuan
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Lin, Chih Lung
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Chao, Chuen Guang
;
Liu, Tzeng Feng
;
材料科學與工程學系
The as-quenched microstructure of the Fe-30%Mn-9%Al-5%Cr-0.7%C (in mass%) alloy was single-phase austenite. When the as-quenched alloy was aged at 550 degrees C-750 degrees C, fine (Fe,Mn)(3)AlC carbides were formed within the austenite matrix. In addition, as the aging temperature increased, a M7C3 carbide + D0(3) -> M7C3 carbide + B-2 -> M7C3 carbide + alpha (ferrite) phase transition had occurred on the grain boundaries. This grain boundary precipitation behavior has never before been observed in FeMnAlC and FeMnAlCrC alloy systems.
Relationship between Microstructures and Tensile Properties of an Fe-30Mn-8.5Al-2.0C Alloy
(2010-06-01)
Lin, Chih Lung
;
Chao, Chuen Guang
;
Bor, Hui Yum
;
Liu, Tzeng Feng
;
材料科學與工程學系
Owing to the presence of a large amount of fine (Fe,Mn)(3)AlC carbides within austenite (gamma) matrix, the tensile property of the Fe-30%Mn-85Al%-20%C (in mass%) alloy in the as-quenched condition was clearly superior to that of the as-quenched FeMnAlC (C <= 1 3%) alloys investigated by previous workers After being aged at 823 K for 3 h, the present alloy could possess high yield strength up to 1262 MPa with an excellent 32 5% elongation With almost equivalent ductility. the yield strength obtained was about 16% higher than that of the FeMnAlC (C <= 1 3%) alloys after solution heat-treatment or controlled-rolling followed by an optimal aging at 823 K Additionally, due to the pre-existing fine (Fe,Mn)(3)AlC carbides within the gamma matrix in the as-quenched alloy, the aging time required for attaining the optimal combination of strength and ductility was much less than that of the FeMnAlC (C <= 1 3%) alloys aged at 823 K When the present alloy was aged at 823 K for a time period longer than 4 h. both the strength and ductility were drastically dropped due to the occurrence of gamma(0)/kappa (gamma(0) carbon-deficient austenite) lamellar structure on the gamma/gamma gram boundaries [doi 10.2320/matertrans.M2010013]