熱力学諸量の測定とその結果を用いた化学熱力学計算によるNi-Mo-BおよびNi-W-B 3成分系状態図の決定

抄録

The phase diagrams of the Ni-Mo-B and Ni-W-B ternary systems in the region of less than 50mol%B were constructed by thermodynamic calculation, based on the data obtained by thermodynamic measurement of the related materials. We found three ternary eutectic points and three or two ternary peritecto-eutectic points as follows:
E₁:L (1365K, 71.5mol%Ni-6.0mol%Mo-22.5mol%B)=(Ni)+Ni₃B+NiMo₂B₂
E₂:L (1355K, 62.5mol%Ni-2.5mol%Mo-30.5mol%B)=Ni₃B+Ni₂B+NiMo₂B₂
E₃:L (1445K, 42.0mol%Ni-30.6mol%Mo-10.3mol%B)=(Ni)+NiMo+NiMo₂B₂
P₁:L (1812K, 34.9mol%Ni-42.3mol%Mo-22.8mol%B)+MoB=Mo₂B+NiMo₂B₂
P₂:L (1633K, 42.3mol%Ni-40.4mol%Mo-17.3mol%B)+Mo=Mo₂B+NiMo₂B₂
P₃:L (1812K, 53.5mol%Ni-33.7mol%Mo-12.8mol%B)+Mo=NiMo+NiMo₂B₂
E₁:L (1622K, 51.0mol%Ni-31.6mol%W-17.4mol%B)=(Ni)+W+NiW₂B₂
E₂:L (1260K, 71.0mol%Ni-7.0mol%W-22.0mol%B)=(Ni)+Ni₃B+NiW₂B₂
E₃:L (1291K, 65.4mol%Ni-4.8mol%W-29.8mol%B)=Ni₂B+Ni₃B+NiW₂B₂
P₁:L (2115K, 23.8mol%Ni-43.1mol%W-33.1mol%B)+WB=W₂B+NiW₂B₂
P₂:L (1657K, 48.9mol%Ni-33.1mol%W-18.0mol%B)+W₂B=W+NiW₂B₂
The calculated phase diagrams are expected to be useful for the development of new Ni-based heat-, corrosion- or wear-resistance alloys.