Jianlie Liang

Intermetallics and phase transformations of the Zr-1.0Sn-0.3Nb-0.3Fe-0.1Cr alloy

Intermetallics and phase transformations of the zirconium-based alloy, Zr-1.0Sn-0.3Nb-0.3Fe-0.1Cr, were investigated by conventional X-ray diffraction (XRD), differential scanning calorimetry (DSC), and dilation measurement. Three types of precipitates, namely, (ZrNb)2Fe, Zr(CrFe)2, and Zr3Fe, were detected by XRD. The cubic Ti2Ni-type (ZrNb)2Fe was found to be the main precipitate in the alloy, and it was proposed to dissolve at 861°C, whereas Zr3Fe dissolved at 780°C and Zr(CrFe)2 at 814°C. No precipitates were observed at a temperature higher than 900°C. The transformation-start temperature of α-Zr → β-Zr was reconfirmed to be 780°C, and the end temperature of α-Zr → β-Zr was determined to be 955°C. The dilation result also revealed that the martensitic transformation-start temperature, Ms, and the finish temperature, Mf, of this alloy were 741°C and 645°C, respectively.

Isothermal section of Gd-Sm-Co ternary system at 773 K

Abstract The isothermal section of the phase diagram of the Gd-Sm-Co ternary system at 773 K was investigated by X-ray powder diffraction (XRD), differential thermal analysis (DTA)optical microscopy and scanning electron microscopy (SEM) techniques. The result shows that the isothermal section consists of 12 single-phase regions, 16 two-phase regions and 5 three-phase regions. Five pairs of corresponding compounds of Gd-Co and Sm-Co systems, i.e., Gd 2 Co 17 and Sm 2 Co 17 , Gd 2 Co 7 and Sm 2 Co 7 , GdCo 3 and SmCo 3 , GdCo 2 and SmCo 2 , Gd 3 Co and Sm 3 Co form continuous series of solid solutions. The maximum solid solubility of Sm in Gd 4 Co 3 and Gd 12 Co 7 were about 7.2 at.% and 47.8 at.% Sm, respectively. The maximum solid solubility of Gd in Sm 5 Co 19 and Sm 5 Co 2 were about 4.7 at.% and 7.6 at.% Gd, respectively. The binary compounds Sm 9 Co 4 , GdCo 5 and SmCo 5 were not observed at 773 K. No ternary compound was found.