TY - JOUR
T1 - Experimental study on phase relationships in the Si-rich portion of the Nb-Si-W ternary system
AU - Li, Yan
AU - Li, Changrong
AU - Du, Zhenmin
AU - Guo, Cuiping
AU - Li, Jingbo
PY - 2013
Y1 - 2013
N2 - This paper describes the experimental study on liquidus projection and the isothermal section at 1873 K of the Nb-Si-W ternary system in the Si-rich portion. The microstructures and solidification paths of the as-cast alloys were analysed. The constituent phases and their equilibrium compositions of the as-cast+heat-treated alloys were determined. The microstructure observation, the phase identification and the composition measurement were performed using scanning electron microscopy (SEM), X-ray diffraction (XRD) and electron probe microanalysis (EPMA), respectively. No ternary compound was found. For the liquidus projection in the investigated Si-rich portion, there exist four primary solidification regions, Diamond-Si, β(Nb,W)5Si 3, Nb(W)Si2 and W(Nb)Si2, and two eutectic invariant reactions, L→β(Nb,W)5Si3+W(Nb)Si 2+Nb(W)Si2 and L→W(Nb)Si2+Nb(W)Si 2+Diamond-Si. The type of the latter invariant reaction was determined with the help of the thermodynamic assessment of the system. Together with literature reported investigations for the Nb-W-rich portion, the whole liquidus projection of the Nb-Si-W ternary system was constructed. For the isothermal section at 1873 K in the investigated Si-rich portion, there are three three-phase regions, liquid+Nb(W)Si2+W(Nb)Si2, Nb(W)Si2+αNb(W)5Si3+β(Nb,W) 5Si3 and Nb(W)Si2+W(Nb)Si2+β (Nb,W)5Si3, and seven two-phase regions, liquid+Nb(W)Si2, Nb(W)Si2+αNb(W)5Si 3, αNb(W)5Si3+β(Nb,W) 5Si3, Nb(W)Si2+β(Nb,W)5Si 3, liquid+W(Nb)Si2, Nb(W)Si2+W(Nb)Si 2 and W(Nb)Si2+β(Nb,W)5Si3.
AB - This paper describes the experimental study on liquidus projection and the isothermal section at 1873 K of the Nb-Si-W ternary system in the Si-rich portion. The microstructures and solidification paths of the as-cast alloys were analysed. The constituent phases and their equilibrium compositions of the as-cast+heat-treated alloys were determined. The microstructure observation, the phase identification and the composition measurement were performed using scanning electron microscopy (SEM), X-ray diffraction (XRD) and electron probe microanalysis (EPMA), respectively. No ternary compound was found. For the liquidus projection in the investigated Si-rich portion, there exist four primary solidification regions, Diamond-Si, β(Nb,W)5Si 3, Nb(W)Si2 and W(Nb)Si2, and two eutectic invariant reactions, L→β(Nb,W)5Si3+W(Nb)Si 2+Nb(W)Si2 and L→W(Nb)Si2+Nb(W)Si 2+Diamond-Si. The type of the latter invariant reaction was determined with the help of the thermodynamic assessment of the system. Together with literature reported investigations for the Nb-W-rich portion, the whole liquidus projection of the Nb-Si-W ternary system was constructed. For the isothermal section at 1873 K in the investigated Si-rich portion, there are three three-phase regions, liquid+Nb(W)Si2+W(Nb)Si2, Nb(W)Si2+αNb(W)5Si3+β(Nb,W) 5Si3 and Nb(W)Si2+W(Nb)Si2+β (Nb,W)5Si3, and seven two-phase regions, liquid+Nb(W)Si2, Nb(W)Si2+αNb(W)5Si 3, αNb(W)5Si3+β(Nb,W) 5Si3, Nb(W)Si2+β(Nb,W)5Si 3, liquid+W(Nb)Si2, Nb(W)Si2+W(Nb)Si 2 and W(Nb)Si2+β(Nb,W)5Si3.
KW - Isothermal section
KW - Liquidus projection
KW - Microstructure
KW - Nb-Si-W ternary system
KW - Solidification path
UR - http://www.scopus.com/inward/record.url?scp=84875150898&partnerID=8YFLogxK
U2 - 10.1016/j.calphad.2013.01.002
DO - 10.1016/j.calphad.2013.01.002
M3 - Article
AN - SCOPUS:84875150898
SN - 0364-5916
VL - 41
SP - 60
EP - 70
JO - Calphad: Computer Coupling of Phase Diagrams and Thermochemistry
JF - Calphad: Computer Coupling of Phase Diagrams and Thermochemistry
ER -