Microstructure and mechanical properties of directionally solidified Fe–Al–Nb eutectic

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• 作者：Srdjan Milenkovic ; Martin Palm
• 关键词：A. Iron aluminides ; based on Fe₃Al ; B. Mechanical properties at high temperatures ; B. Texture ; B. Yield stress ; D. Microstructure
• 刊名：Intermetallics
• 出版年：2008
• 出版时间：October 2008
• 年：2008
• 卷：16
• 期：10
• 页码：1212-1218
• 全文大小：1656 K

文摘

An Fe–26Al–9.5Nb (in at. % ) eutectic alloy produced by directional solidification (DS) has been characterised regarding its microstructure and basic mechanical properties and the latter are compared with an as-cast (AC) alloy of about the same composition. The DS alloy exhibits a regular fibrous eutectic Fe₃Al + (Fe,Al)₂Nb (Laves phase) microstructure. By electron backscatter diffraction (EBSD) it was found that the growth directions are <111> for Fe₃Al and <1120> for (Fe,Al)₂Nb. The compressive yield strength and compressive creep strength under constant and step-wise increased load for the DS and AC alloy are compared with each other. During creep testing the DS alloy showed high microstructural stability, i.e. only slight coarsening was observed. At 650 °C the DS alloy exhibits creep properties which are better than for binary Fe–Al alloys and which are comparable to P92, a state-of-the-art steel for steam turbine applications. The alloy showed a low mass gain after long-time creep testing in air indicating a good oxidation resistance.