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本文报道一种fcc结构的Fe-Mn-Al合金(Mn 25.6,Al 4.1,C 0.16,Si0.27 wt-％)在超低温的性能、组织结构与磁性转变。此合金在300—4 K间具有适宜的强度、较高的塑性、韧性与很稳定的奥氏体组织。300 K及4 K的磁化率x_v,分别为34.5×10~(-4)与22×10~(-4)。室温电阻率为105μΩ·cm,低温冷收缩率小于一般Fe-Cr-Ni奥氏体钢。其磁化率(x_v)-温度(T)曲线于320 K左右呈现峰值,dx/dT符号的改变表征发生了顺磁性-反铁磁性转变。同时伴有一些物理性能如弹性模量、热膨胀、电阻率等的反常变化。 Al加入Fe-Mn合金中,明显地降低Néel温度(T_N),提高磁化率,并在T_N点处呈现较大的磁化率峰值。与AISI 300系Cr-Ni奥氏体钢比较,γ-Fe-Mn-Al合金的主要特点为在极低温区(如20—4 K)兼具稳定的奥氏体与极低磁化率,是一种潜在的超导磁体用结构合金。
This paper reports the properties, microstructures and magnetic transitions of fcc-structured Fe-Mn-Al alloys (Mn 25.6, Al 4.1, C 0.16, Si0.27 wt-%) at very low temperatures. This alloy has suitable strength between 300-4 K, high plasticity, toughness and very stable austenitic structure. The magnetic susceptibility x_v of 300 K and 4 K were 34.5 × 10 -4 and 22 × 10 -4, respectively. Room temperature resistivity of 105μΩ · cm, cold shrinkage rate is lower than the general Fe-Cr-Ni austenitic steel. The magnetic susceptibility (x_v) -temperature (T) curve shows a peak around 320 K. The change of dx / dT signifies the paramagnetic-antiferromagnetic transition. Accompanied by some of the physical properties such as elastic modulus, thermal expansion, resistivity and other abnormal changes. The addition of Al into the Fe-Mn alloy significantly decreased the Néel temperature (T_N), increased the magnetic susceptibility and showed a large magnetic susceptibility peak at the T_N point. Compared with the AISI 300 series Cr-Ni austenitic steels, the main feature of the γ-Fe-Mn-Al alloy is that it has both stable austenite and very low magnetic susceptibility in an extremely low temperature region A Structural Alloy for Potential Superconducting Magnets.