摘要
The isothermal section of the phase diagram of the Tb-Fe-Ga ternary system at 773 K was investigated by X-ray powder diffraction analysis.Fourteen binary compounds,TbFe2,TbFe3,Tb6Fe23,a-Tb2Fe17,Tb5Ga3,Tb3Ga2,TbGa,Tb3Ga5,ThGa2,a-TbGa3,a-Fe3Ga,a-Fe6Ga5,Fe3Ga4 and FeGa3,have been confirmed and six ternary compounds,TbFe0.32Ga1.68,TbFe2.4Ga0.6,Tb4FeGa12,Tb2FeGa8,TbFe6Ga6 and ThFe5Ga7,were found in this ternary system at 773 K.The structures of theses compounds were determined by Rietveld refinement method.The compound TbFe0.32Ga1.68 is InNi2-type structure(space group P63/mmc)with a=0.43727(2)and C=0.72930(4)nm.The compound TbFe2.4Ga0.6 belongs to CeNi3-type structure(space group P63/mmc)with a-0.51877(9)and C=1.6621(4)nm.The compound Tb4FeGa12 is U4Re7Si6-type structure(space group Im 3m)with a=0.85576(4)nm.The compound Tb2FeGas is H02CoGa8-type structure(space group P4mmm)with a=0.4259(4)and C=1.1 1 356(8)nm.The compound TbFe6Ga6 is ScFe6Ga6-type structure(space group Immm)with a=0.85551(4),b=0.86826(5)and C=0.50717(3)nm.The compound TbFejGa7 is ThMn12-type structure(space group 14/mmm)with a=0.86779(8)and C=O.50923(5)nm.The isothermal section of this ternary system at 773 K consists of 23 single-phase regions,42 two-phase regions and 22 three-phase regions.The solid solutions this temaly system is formed by substitution of Ga for Fe.The maximum solid solubilities of Ga in ThFe2,ThFe3 and Th2Fe17 are 19.6,8.0,and 37.5 at% respectively.The homogeneity ranges for the other compounds are small.