W-Ni compact is prepared by liquid phase sintering is 1500°C. If the size of the tungsten grains is 40µm and the interfacial tungsten- tungsten and tungsten-nickel energies are 0.52 and 0.30 Jm^{-2} respectively, the predicted average neck size (in µm) of sintered tungsten grain is:

(Melting points of tungsten and nickel are 3410°C and 1453°C, respectively)

(A) 10 (B) 15 (C) 20 (D) 25

Correct answer is option C. Given that γs-s = 0.52 J/m2 and γs-l= 0.30 J/m2 2γs-l cos(Θ/2)=γs-s On simplification, (Θ/2)= 29.92 sin(Θ/2)=( x/2)/(D/2) x=20 μm

Correct answer is option C.

Given that γ

_{s-s}= 0.52 J/m^{2 }and γ_{s-l}= 0.30 J/m^{2 }2γ

_{s-l}cos(Θ/2)=γ_{s-s}On simplification, (Θ/2)= 29.92 sin(Θ/2)=( x/2)/(D/2)

x=20 μm