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| THE SUBSTITUTIONAL-INTERSTITIAL INTERACTION PEAK IN Fe-Ti-N SYSTEM QUENCHED FROM α-PHASE REGION |
| Ge Qinglin;Shi Tiansheng; Chen Tingguo; Chert Yuan; Wu Ziliang (Shanghai Institute of Metallurgy; Academia Sinica;) |
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Cite this article:
Ge Qinglin;Shi Tiansheng; Chen Tingguo; Chert Yuan; Wu Ziliang (Shanghai Institute of Metallurgy; Academia Sinica;). THE SUBSTITUTIONAL-INTERSTITIAL INTERACTION PEAK IN Fe-Ti-N SYSTEM QUENCHED FROM α-PHASE REGION. Acta Metall Sin, 1982, 18(3): 316-325.
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Abstract Wire specimens of Fe-Ti alloys were loaded with nitrogen at 580℃, homogenized at 650℃ and then quenched at 570℃. When internal friction of these specimens were measured at a frequency of 1 Hz, two peaks were observed. The peak located at 20℃ is a normal nitrogen Snoek peak, while the one near 150℃ is the s-i peak (activation energy=1.13 eV). The addition of Ti to α-iron makes the nitrogen Snoek peak unstable, the later decays rapidly even at room temperature, In the range of atomic ratio N/Ti≤1, neither the Snoek peak nor the s-i peak is observed. Only after N/Ti>1, both peaks grow simultaneously with increasing nitrogen concentration. The fact that the height of the s-i peak changes linearly with Ti content indicates the peak to be contributed by reactions involving only isolated Ti atoms and has nothing to deal with either Ti-Ti atomic pairs' or clustering of solute atoms.It is suggested that two types of defects, the Ti-N pair defects and the N-Ti-N triplets, are the reaction centers giving rise to the s-i peak. The pair defects are formed by nitrogen occupation in the T_1-sites. The binding between the two constituent atoms of a pair defect is so strong that the alloys can be deprived of any free nitrogen as long as there are excess Ti atoms remaining in solution. This is the reason for the absence of any peak in the range N/Ti≤1. After N/Ti>1, excess nitrogen atoms will be distributed between the O_Ⅱ-sites and the T_3-sites at a ratio of about 1:10 until majority of the pair defects being transformed into triplets. Over a critical point of N/Ti≈2, almost all of the excess nitrogen atoms are only alloted to the O_Ⅱ-sites of the triplets, and in the mean time, the s-i peak begins to show a rapid increase in relaxation strength of about 10 times.The supersaturated nitrogen atoms frozed in the α-iron matrix during quenching tend to redistribute at room temperature by diffusing into O_Ⅱ-sites (diffusion length～10(?)), so as to make the Snoek peak transient. The profile of the s-i peak is solely determined by the concentration of excess nitrogen and is therefore independent of quenching temperature as well as cooling rate.
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Received: 18 March 1982
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1 Dijkstra, L. J.; Sladck, R. J., Trans. AIME, 197 (1953) , 69．
2 Ritchie, I. G.; Rawlings, R., Acta Metall., 15 (1967) , 491．
3 Fast, J. D.; Mcijcring, J. L., Philips Res. Rep., 8 (1953) , 1．
4 Welch, W. D., Jr.; Carpenter, S. H., Acta Metall., 21 (1973) , 1169．
5 Hasson, D. F.; Arsenault, R. J., Treatise on Materials Science and Technology, Vol. 1, Ed. Herman, H., Academic, Press, New York, 1972, p. 179．
6 Szabo-Miszenti, G., Acta Metall., 18 (1970) , 477．
7 Pope, M.; Jones, D. M.; Jack, K. H., 5th Int. Conf. on Internal Friction and Ultrasonic Attenuation in Crystalline Solids, Eds. Lenz, D.;Lucke, K., Springer-Vcrlag, Berlin, 1975, p. 266．
8 Wert, C.; Marx, J., Acta Metall., 1 (1953) , 113． |
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