Snoek Relaxation in Fe–Cr Alloys and Interstitial–Substitutional Interaction
Snoek Relaxation in Fe–Cr Alloys and Interstitial–Substitutional Interaction
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DOI：
10.1002/1521-396x(199703)160:1
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发表时间：
1997-03
期刊：
影响因子：
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通讯作者：
I. Golovin;M. Blanter;R. Schaller
中科院分区：
文献类型：
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作者：
I. Golovin;M. Blanter;R. Schaller
研究了α-Fe、Fe-Cr铁素体合金和Cr在0.01 ~ 10 Hz范围内的内摩擦（IF）谱。α-Fe中Snoek峰（T max）的温度位置为315 K (1Hz)，从纯Fe开始，以纯Cr结束，均存在Snoek型弛豫。由T-f位移推导出的活化能为0.81 eV。Cr中的tmax为433 K，活化能为1.11 eV。Fe-Cr合金的snoek型峰比纯Fe和纯Cr合金的snoek型峰宽得多，峰与铬含量曲线的温度位置在35 wt% Cr附近出现最大值（T max为573 ~ 578 K， f 1.2 Hz，活化能约为1.45 eV）。重要的是，α-Fe中的Cr原子比铬中的Fe原子对峰的温度位置有更显著的影响。提出了一个基于原子相互作用的新模型来解释组分对Snoek峰位置的影响。利用C-C和c -取代原子相互作用能，用蒙特卡罗方法模拟了内摩擦。C-s相互作用采用了一种远程应变诱导（弹性）相互作用模型，外加固定取代原子周围两个最近配位壳层的化学相互作用。原子间相互作用通过改变碳原子的排列（短程顺序）和八面体间隙中C原子的能量来影响IF，从而改变IF的活化能。当C-Cr在Fe中的第一配位壳层（H化学）的化学相互作用值为-0.15 eV和C-Fe在Cr中的化学相互作用值为+ 0.15 eV时，计算的峰值温度与实验值吻合较好。Cr在α-Fe中的影响和Fe在Cr中的影响的差异是由碳原子和取代原子之间的弹性和化学相互作用的差异来解释的。铬铁基合金中的弛豫过程是由于碳原子在应力作用下在Cr原子周围的第一和第二配位壳层的八面体间隙之间扩散，以及在Cr基合金中，在Fe原子周围的第二和第三配位壳层之间扩散。
The internal friction (IF) spectra of α-Fe, Fe-Cr ferritic alloys and Cr have been investigated in a frequency range of 0.01 to 10 Hz. A Snoek-type relaxation was found in all the investigated C doped Fe-Cr alloys, starting from pure Fe and finishing with pure Cr. The temperature location of the Snoek peak (T max ) in α-Fe was found to be 315 K (1Hz). The activation energy deduced from the T-f shift was 0.81 eV. T max in Cr was 433 K with an activation energy of 1.11 eV. The Snoek-type peaks in Fe-Cr alloys are much wider than in pure Fe or pure Cr. The temperature location of the peak versus chromium content curve exhibits a maximum in the vicinity of 35 wt% Cr (T max was 573 to 578 K, f 1.2 Hz and the activation energy was about 1.45 eV). It is important that Cr atoms in α-Fe have a more pronounced influence on the temperature location of the peak than Fe atoms have in chromium. A new model based on the atomic interactions is proposed to explain the influence of composition on Snoek peak location. The internal friction has been simulated by a Monte Carlo method, using C-C and C-substitutional atom (s) interaction energies. A model of long-range strain-induced (elastic) interaction supplemented by the chemical interaction in the two nearest coordination shells around an immobile substitutional atom was used for the C-s interaction. The interatomic interaction was supposed to affect IF by changing both the carbon atom arrangement (short-range order) and the energy of C atoms in octahedral interstices, and therefore the activation energy of IF. The peak temperatue calculated coincides well with the experimental ones if the value for the chemical interaction in the first coordination shell (H chem ) for C-Cr in Fe is -0.15 eV and for C-Fe in Cr + 0.15 eV. The difference in the influence of Cr in α-Fe and Fe in Cr is accounted for by a difference in the elastic and chemical interaction both between the carbon atoms and the substitutional atoms. The relaxation process in chromium Fe-based alloys is due to the carbon atom diffusion under stress between octahedral interstices of first and second coordination shells around the Cr atoms, and in Cr-based alloys, between second and third shells around the Fe atoms.