Thermodynamic assessment of the Nb–Ge system

Experimental and thermodynamic assessment of the Ge-Nb-Si ternary phase diagram

“…The Ge-Nb system was modelled by Geng et al [10]. The Ge-Nb system contains 3 intermetallic phases; Nb 3 Ge (cP8 Cr 3 Si -type), Nb 5 Ge 3 (tI32 W 5 Si 3 type), NbGe 2 (hP9 CrSi 2 type), and 2 solid solution phases; Nb (cI2 Im-3m) and Ge (cF8 Fd-3m) as shown in Fig.…”

“…The Ge-Nb system contains 3 intermetallic phases; Nb 3 Ge (cP8 Cr 3 Si -type), Nb 5 Ge 3 (tI32 W 5 Si 3 type), NbGe 2 (hP9 CrSi 2 type), and 2 solid solution phases; Nb (cI2 Im-3m) and Ge (cF8 Fd-3m) as shown in Fig. 2 [10]. When plotting the diagram using the published dataset a small inadvertent miscibility gap was seen at the Nb 3 Ge-liquid phase boundary (Figure 2a In the previously reported literature [11][12][13][14] there is a conflict over the prototype structure of the Nb 5 Ge 3 phase, whether it has the Cr 5 B 3 or W 5 Si 3 prototype.…”

“…In the following work the hexagonal phase will be referred to as Nb 10 Ge 7 . Due to the uncertainty of the stability of this phase, Geng et al [10] reported two calculated phase diagrams for the Ge-Nb system; one containing the phase Nb 10 Ge 7 and one without ( Fig. 2 is based on the latter).…”

Determinação Experimental Das Relações De Fases Do Sistema Nb-Ti-Si Na Seção Isotérmica a 1.200°C

“…Porém, observa-se poucos campos de equilíbrio trifásico bem definidos, e muitas incertezas com relação à maioria dos campos propostos. Geng et al [20] fizeram o cálculo termodinâmico da projeção liquidus e das seções isotérmicas a 1000 °C, 1150 °C e 1200 °C do sistema NbTiSi. Os compostos binários possivelmente não-estequiométricos, como αNb5Si3, βNb5Si3, NbSi2 e Ti5Si3, foram considerados e todos os compostos ternários foram extrapolados das fases binárias.…”

“…A capacidade térmica das fases intermetálicas αNb5Si3, βNb5Si3, NbSi2 foram calculadas usando as regras de Neumann-Kopp. A seção isotérmica a 1200°C calculada por Geng et al [20], Figura 1b, define os campos ternários Nb5Si3 + (Nb, Ti)3Si + (Nb, Ti, Si), Nb5Si3 + (Nb, Ti)3Si + Ti5Si3, Ti5Si3 + (Nb, Ti)3Si + (Nb, Ti, Si), Nb5Si3 + Ti5Si4 + Ti5Si3, Nb5Si3 + Ti5Si4 + NbSi2, NbSi2 + Ti5Si4 + TiSi, NbSi2 + TiSi2 + TiSi e NbSi2 + TiSi2 + SiSS. …”