List of top Metallurgy Questions asked in GATE MT

An alloy having composition W-20 wt.% Ni is prepared by mixing elemental powders. The resulting powder mixture is liquid phase sintered at \(1550^{\circ}\text{C}\) for 1 hour. The liquid phase sintered microstructure consists of interconnected, spherical tungsten grains dispersed in nickel. The tungsten grain size is 70 \(\mu\text{m}\) and the W-W interparticle neck diameter is 35 \(\mu\text{m}\). If W-Ni interfacial energy is 0.30 J/m\(^2\), the W-W interfacial energy (in J/m\(^2\)), rounded off to two decimal places is ______.
(Given: melting point of W: \(3410^{\circ}\text{C}\) and melting point of Ni: \(1455^{\circ}\text{C}\))
Iron powder is compacted at room temperature to 75% of its theoretical density. The as-pressed iron compact is sintered in inert-gas atmosphere at \(1200^{\circ}\text{C}\) to 90% of its theoretical density. Assuming isotropic shrinkage, the linear shrinkage (in percent) undergone by the iron compact during sintering (rounded off to one decimal place) is ______ %.
In optical microscopy, which one of the following combinations of wavelength (\(\lambda\)) and numerical aperture (NA) provides the best spatial resolution?
In optical microscopy, which one of the following combinations of wavelength ($\lambda$) and numerical aperture (NA) provides the best spatial resolution?