Mössbauer Spectroscopy of α'-Phase of Fe- 69.7%Cr Alloy at Low Temperature
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摘要: Fe-69.7%(atom)Cr合金经500℃时效4年后,获得单一α'相结构,并测定了它在低温下合金的穆斯堡尔谱。结果表明:在室温300K穆斯堡尔谱为一单线洛仑兹线型,降低温度其半宽度也随着展宽,在77K时超精细场达3072.20kA/m;超精细场数值随温度降低而增大,其变化规律与顺磁体模型理论值变化曲线相似,说明α'相在77K以上为一顺磁质,从1200℃至室温通过变温热循环加速了Cr句晶界扩散以及顺磁α'相在Fe-24.6%Cr-5.0%Al合金中析出,并导致合金脆化。Abstract: A α'-phase structure is got after Fe-69.7%(atom)Cr alloy aging for four years at 500℃. Its Mössbauer spectrum characteristic is determined. The results indicate the Mössbauer spectrum obtained at 300 K is a pure Lorentzian lineshape, the overall width of composite absorbed spectrum increases considerable with temperature droping, and the range of superfine field reaches about 3 072.20kA/m at 77 K. The behaviour of superfine field is similar to that of ideal paramagnetic model. This phenomenon demonstrates that the α'-phase is a paramagnet above 77K. By thermal cycling treatment from 1200℃ to room temperature, a considerable acceleration of Cr atom diffusion to grain boundaries and α'-phase precipitation in Fe-24.6%Cr-5%Al alloy occurres, and which cause the alloy embrittlement.
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Keywords:
- Mössbauer spectrum /
- superfine field /
- paramagnet
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