Study on Elevated-Temperature mechanical properties of Iron-Aluminide Base alloy

• Main Authors: Liu, I-Ming, 劉倚銘
• Other Authors: J.P. Chu
• Format: Others
• Language: en_US
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/89179808775105472302

碩士 === 國立海洋大學 === 材料工程研究所 === 85 === Elevated-temperature mechaincal properties of iron-aluminide base alloys have been studied. Alloys investgated included binary and ternary with additions of macro- and microalloying elements (such as Cr,Zr,Si,Nb). Fe-17Al,Fe-27Al and Fe-35Al (in at%) were selected as binary series. Ordered B2 crystal structure was obtained for all alloys after annealing. After application of thermochanical treatment, tensile tests at various temperatures (500-800) were carried out in air. results showed that elongation of low Al-content (<23%) alloys decreased with increasing temperature between 600-800, whereas for high Al-content (>23%) alloys elongation increased with increasing temperature between 500-800. Addition of alloying elements could obviously refine grain structure, but yielded no measurement improvement in ductility. The strength of all alloys showed dramatically drops at 600. In this study, Fe-27Al showed the best elongation (180%) at 800, while Fe-35Al-5Cr-0.1Zr-0.05B exhibited the maximum tensile strength (500MPa) at 500 among Fe-Al alloys.No hydrogen embrittlement effect was thus found in the test temperature range. Expect Fe-35Al and Fe-35Al -5Cr-0.1Zr-0.05B alloys showing a brittle transgranular cleavage fracture, all other Fe-Al alloys exhibited dimple or necking ductile fracture features. Sectional microstructureal observations indicated several types of grain structures: elongated grains, cavitations as well as small recrystallized grins due to the dynamic recrystallization during the test. (Keyword: iron-aluminide base alloys, B2, thermochanical teratment, hydrogen embrittlement, superplasticity, dynamic recrystallization.)