【摘要】 在轮速为40 m·s-1快淬制备不同Fe含量的亚稳态快淬SmFe x(x=7.5,8.0,8.5,9.0,9.5,10.0,10.5,11.0,12.0,13.0)合金,经过800℃退火处理60 min,采用XRD分析了快淬SmFe x合金退火前后的相组成和晶体结构,并结合Rietveld结构精修方法分析了TbCu7型SmFe9相的晶体结构。结果表明:快淬SmFe x合金在化学计量数SmFe x(x=7.5~8.0)时,形成Th2Zn17型Sm2Fe17和少量的SmFe2;随着Fe含量增加,在x=8.5~13.0时,由平衡相转变成亚稳TbCu7型SmFe9相,α-Fe含量逐渐增多。随着Fe含量增加,SmFe合金的晶格常数a不断减小,而晶格常数c,c/a不断增大。在TbCu7型SmFe9相中Fe原子分别位于2e,3g,6l晶位,Sm原子自由占据1a晶位。2e晶位哑铃状Fe-Fe原子对的的占位趋于无序。退火后SmFe x合金在化学计量数x=8.5,9.0时,由亚稳相TbCu7型SmFe9转变为平衡Th2Zn17型Sm2Fe17相;在化学计量数SmFe x(x=9.5~13.0)时,保持TbCu7型SmFe9不变。退火使2e晶位哑铃状Fe-Fe原子对有序排列,Sm原子在1a晶位的占位率提高,晶体结构由TbCu7型结构转变成Th2Zn17型结构,但Fe含量超过一定值后,无法继续这种转变。退火SmFe x合金晶体结构的晶胞参数变化规律与淬火态相同,退火SmFe合金中α-Fe含量增多。更多还原

【Abstract】 Metastable SmFe x( x =7. 5,8. 0,8. 5,9. 0,9. 5,10. 0,10. 5,11. 0,12. 0,13. 0) alloys were prepared by rapid quenching and the phases and crystal structure were investigated in the as-quenched state and after annealing at 800 ℃ for 60 min by X-ray diffraction( XRD). Rietveld analysis was applied to study the crystal structure of SmFe9phase of TbCu7-type. The results showed that in stoichiometric SmFe x for x = 7. 5 ~ 8. 0,Th2Zn17-type Sm2Fe17 phases and a bit amount of SmFe2 were formed,TbCu7-type SmFe9phase rather than Th2Zn17-type structure was obtained by increasing the proportion of Fe( x = 8. 5 ~ 13. 0),and the content of α-Fe increased. Lattice parameters a decreased,but lattice parameters c and axial ratio c / a increased with the increase of Fe content. Sm was freely located in 1a position,Fe atoms in 2e site,3g site,6l site in TbCu7-type SmFe9 phases and dunbbell pairs of Fe-Fe randomly occupied 2e site. By annealing SmFe x alloys at x = 8. 5,9. 0,Th2Zn17-type Sm2Fe17 phase was obtained from TbCu7-type structure,and at x = 9. 5 ~ 13. 0,TbCu7-type SmFe9 phase remained. Fe atoms at 2e site occupied an ordered arrangement,Sm atoms occupying ratio increased after annealing. Th2Zn17-type structures were transformed from TbCu7-type structure in annealed SmFe x alloys,but this transformation was prohibited when x increased to a certain content. Variation of lattice parameters of annealed Sm-Fe alloys was the same as the quenched,but α-Fe increased after annealing.更多还原