The effects of chromium on the microstructure and tensile behavior of Fe₃₀Ni₂₀Mn₃₅Al₁₅

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• 作者：Fanling Meng ; Jingwen Qiu ; Ian Baker
• 关键词：FeNiMnAl alloys ; Microstructure ; Tensile properties ; Environmental embrittlement ; High temperature strength
• 刊名：Materials Science and Engineering: A
• 出版年：2013
• 出版时间：1 December, 2013
• 年：2013
• 卷：586
• 期：Complete
• 页码：45-52
• 全文大小：4955 K

文摘

The effects of different additions of chromium (¡Ü8 at. % ) on both the microstructure and room-temperature flow and fracture behavior of as-cast Fe₃₀Ni₂₀Mn₃₅Al₁₅ have been investigated. For ¡Ü6 at. % Cr, the microstructure was lamellar consisting of (Ni, Al)-rich B2 and (Fe, Mn)-rich f.c.c. phases with most of the Cr residing in the f.c.c. phase, whilst the addition of 8 at. % Cr produced a more complex microstructure. The room-temperature elongation to failure at a strain rate of 5¡Á10^?4 s^-1 increased with increasing Cr from 6.5 % for the Cr-free material to ~18 % at 6 at. % Cr, and then decreased dramatically for 8 at. % Cr to 6.3  % . Concomitantly, the yield stress decreased slightly from 820 to 679 MPa as the Cr content increased to 6 at. % , and then increased to 819 MPa for 8 at. % Cr. The addition of 6 at. % Cr also resulted in the complete suppression of the environmental embrittlement that is observed at slow strain rate at room temperature in the Cr-free alloy , i.e. at a strain rate of 3¡Á10^?6 s^?1 unalloyed Fe₃₀Ni₂₀Mn₃₅Al₁₅ showed only 0.7 % elongation, whereas the alloy with 6 at. % Cr exhibited 18 % elongation. The 6 at. % Cr modified alloy showed a similar temperature dependence of the yield strength as the Cr-free alloy , with the yield strength decreasing steadily to 150 MPa at 1000 K. Interestingly, the elongation to failure was largely independent of temperature for this alloy.