An alloy having composition W-20 wt.% Ni is prepared by mixing elemental powders. The resulting powder mixture is liquid phase sintered at 1550 °C for 1 hour. The liquid phase sintered microstructure consists of interconnected, spherical tungsten grains dispersed in nickel. The tungsten grain size is 70 µm and the W-W interparticle neck diameter is 35 µm. If W-Ni interfacial energy is 0.30 J/m², the W-W interfacial energy (in J/m²), rounded off to two decimal places is ___________________
(Given: melting point of W: 3410 °C and melting point of Ni: 1455 °C)