Isothermal Section Of The Gd-Ge-Si Ttrnary System At 900℃

Phase equilibria in the Gd-rich Gd-Ge-Si ternary system (Gd ≥40at.%) at 900 ℃ were investigated by X-ray powder diffraction and DSC. The binary compounds, Gd5Ge3,Gd5Si3,Gd5Ge4,Gd5Si4,GdGe,GdSi,Gd2Ge3 and Gd2Si3, and the ternary compound Gd5(Gel-xSix)4 have been confirmed. The isothermal section of this system at 900 ℃ were constructed. It is composed of 8 single-phase regions,10 two-phase regions and 6 three-phase regions. Two ternary solid solutions, Gd5(Ge,Si)3 formed between Gd5Ge3 and Gd5Si3(Mn5Si3-type), and Gd2(Ge,Si)3 formed between Gd2Ge3 and Gd2Si3(AIB2),were found in this isothermal section. The maximum solid solubilities of Si in Gd5Ge4 and GdGe at 900℃ are 10.3 and 35.0 at.% respectively, while those of Ge in Gd5Si4 and GdSi at 900℃ are 20.5 and 11.5 at.% respectively. The homogenous range of Gd5(Gel-xSix)4 if from 13.3 to 22.0 at.% Si.