Phase Transformations of the Fe-25Cr-6Ni-2.5Cu Alloys

• Main Authors: Feng-Yao Lin, 林鳳耀
• Other Authors: Chih-Yeh Chao
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/11535892192820204858

碩士 === 國立屏東科技大學 === 機械工程系所 === 98 === Abstract Student ID: N9632003 Title of Thesis: Phase Transformations of the Fe-25Cr-6Ni-2.5Cu Alloys Total Pages: 54 Name of Institute: National Pingtung University of Science and Technology Name of Department: Department of Mechanical Engineering Date of Graduation: .January, 2010 Degree Conferred: Master Name of Student: Feng-Yao Lin Adviser: Dr. Chih-Yeh Chao The Contents of Abstract in this Thesis: The main purposes of the present studies are to analyze the phase transformations of the Fe-25Cr-6Ni-2.5Cu cast alloy. Based on the present studies, some results are described as following. Being solution treatment 1050℃ for 1 hour, the microstructure of the alloy are a mixture of austenite and ferrite duplex phase. The lattice parameter of austenite and ferrite phase are a=3.65Å and a=2.86Å, respectively. In addition, some annealing twin is observed within austenite matrix. The orientation relationship of these twin are found as [011]//[011], (111)//(111), or [011]//[014], (200)//(221). After being solution treatment at 1050℃ for 1 hour then aged at in the range of the 400 and 750℃ for a short time( below 8 hours), no precipitates are found neither the grain boundary or within the matrix. Increasing the aged time to 12 hours or above, a phase transition,γ→γ + ε + M23C6, is found within the γ matrix or on the were α/γ grain boundary when aged at temperature in the range between 400 and 550℃. The lattice parameter ofεand M23C6 phase are a=3.65Å and a=2.86Å, respectively. Moreover, when aged at 600~750℃,a phase transition,γ→γ + MC + M23C6, is found. The lattice parameter of MC phase is a=4.30Å. Due to the precipitation on the grain boundary, the hardness of the ally cast increases and of ductile decreased. Keyword: austenite, ferrite,εphase, MC carbide, M23C6 carbide