GAS-PHASE INTERSTITIAL MODIFICATION OF RARE-EARTH INTERMETALLICS

被引:49
作者
COEY, JMD
SKOMSKI, R
WIRTH, S
机构
[1] Department of Pure and Applied Physics, Trinity College
关键词
D O I
10.1109/20.179483
中图分类号
TM [电工技术]; TN [电子技术、通信技术];
学科分类号
0808 ; 0809 ;
摘要
The gas phase interstitial modification of rare-earth intermetallics is studied. Net reaction energies for nitrogen in Sm2Fe17 and Nd(Fe11Ti) are U0 = - 57 kJ/mole and U0 = - 51 kJ/mole, respectively. The equilibrium nitrogen concentration is calculated as function of temperature and gas pressure using a simple lattice gas model. For nitrogen in Sm2Fe17, refined diffusion parameters D0(N) = 1.02 mm2/s and E(a)(N) = 133 kJ/mole, determined by thermopiezic analysis of the initial stage of nitrogen absorption, are used to calculate nitrogen profiles and the time dependence of the mean nitrogen content during nitrogenation. Similiar values are obtained for nitrogen in Nd(Fe11Ti), whereas the activation energies for hydrogen in Sm2Fe17 and Nd(Fe11Ti) are 31 kJ/mole and 45 kJ/mole, respectively. The elastic stress and strain profiles during nitrogenation are calculated. Important results are a large uniaxial strain near the surface of non-uniformly nitrided particles, and core expansion even in the absence of any nitrogen there. Curie temperature and K1 profiles are calculated and suggestions are made regarding the influence of stress on coercivity and disproportionation of the material.
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页码:2332 / 2337
页数:6
相关论文
共 15 条
[1]  
BOCHSTEIN BS, 1978, DIFFUSION METALS
[2]   STRUCTURE AND MAGNETIC-PROPERTIES OF R2FE17NX COMPOUNDS [J].
BUSCHOW, KHJ ;
COEHOORN, R ;
DEMOOIJ, DB ;
DEWAARD, K ;
JACOBS, TH .
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, 1990, 92 (01) :L35-L38
[3]   SM2FE17NX - SITE AND VALENCE OF THE INTERSTITIAL NITROGEN [J].
CAPEHART, TW ;
MISHRA, RK ;
PINKERTON, FE .
APPLIED PHYSICS LETTERS, 1991, 58 (13) :1395-1397
[4]   GAS-PHASE CARBONATION OF R2FE17 - R = Y, SM [J].
COEY, JMD ;
HONG, S ;
OTANI, Y ;
HURLEY, DPF .
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, 1991, 98 (1-2) :76-78
[5]   NITROGENATION OF R2FE17 COMPOUNDS - R = RARE-EARTH [J].
COEY, JMD ;
LAWLER, JF ;
SUN, H ;
ALLAN, JEM .
JOURNAL OF APPLIED PHYSICS, 1991, 69 (05) :3007-3010
[6]   IMPROVED MAGNETIC-PROPERTIES BY TREATMENT OF IRON-BASED RARE-EARTH INTERMETALLIC COMPOUNDS IN AMMONIA [J].
COEY, JMD ;
SUN, H .
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, 1990, 87 (03) :L251-L254
[7]  
Fast JD., 1976, GASES METALS, DOI 10.1007/978-1-349-81499-2
[8]  
ISNARD O, 1992, IN PRESS PHYS REV B
[9]  
KUTTNER R, 1982, PHYS REV B, V26, P2967
[10]  
LI YP, 1991, PHYS STATUS SOLIDI B, V166, pK107