List of top Engineering Materials Science Questions on Material Science asked in GATE XE

In an FCC crystal with lattice parameter \(a\), consider the reaction of two leading partial dislocations, AB and CD, at the line of intersection of their slip planes \((111)\) and \((\bar{1}11)\), respectively. Dislocations AB and CD have Burgers vectors \(\vec{b}_1\) and \(\vec{b}_2\), respectively, as given in the figure. Which one of the following options for the slip plane and the Burgers vector of the resulting dislocation is correct?

At 873 K, hydrogen diffuses under steady state through a 5 mm thick palladium sheet with a cross-sectional area of 0.3 m\(^2\). The concentrations of hydrogen at high and low pressure ends of the sheet are 3 kg m\(^{-3}\) and 0.5 kg m\(^{-3}\). The amount of hydrogen (in kg per day) passing through the sheet is (rounded off to two decimal places). Given: At 873 K, diffusivity of hydrogen = \(1.8 \times 10^{-8}\, m^2/s\).

A diffraction pattern is obtained from a powdered sample of a pure element, which has FCC crystal structure. If \(x\) and \(y\) are the Bragg angles of the first and the third peaks, respectively, then the ratio \(\dfrac{\sin y}{\sin x}\) is (rounded off to one decimal place).

For a pure element with a BCC crystal structure, the surface energies per unit area of \(\{100\}\) and \(\{110\}\) free surfaces are \(S_{100}\) and \(S_{110}\), respectively. The ratio \(\dfrac{S_{100}}{S_{110}}\) is (rounded off to one decimal place).

The TTT diagram for eutectoid steel is shown below. The steel after complete austenitization at 1073 K is rapidly cooled to different temperatures and held for varying times (as indicated in Column I) followed by quenching to 300 K. Assuming isothermal transformation, match the heat treatment conditions in Column I with the corresponding microstructure in Column II.

Which of the following phenomenon/phenomena contribute to intensity loss of electromagnetic radiation during transmission through a medium?

Match the detector for a scanning electron microscope (SEM) in Column I with the resulting output in Column II. SE: Secondary electrons; BSE: Backscattered electrons; EDS: Energy Dispersive Spectroscopy; EBSD: Electron Backscatter Diffraction \begin{tabular}{|c|c|} \hline Column I & Column II \\ \hline (P) SE Detector & (1) Elemental composition analysis \\ (Q) BSE Detector & (2) Kikuchi lines \\ (R) EDS Detector & (3) Topographic image \\ (S) EBSD Detector & (4) Compositional contrast image \\ \hline \end{tabular}

The figure below shows a plane PQR in a unit cell. The Miller indices of the plane PQR is ...........

The unit of measurement for magnetic dipole moment of a body is:

$B$ is the magnetic flux density and $T_c$ is the critical temperature. The Meissner effect is represented by:

For Al – 4.5 wt% Cu alloy, the correct sequence of precipitation during age hardening at room temperature is:

There is NO base-centered cubic lattice among the list of 14 Bravais lattices because of one or more of the following reasons:

For a conventional optical microscope, which of the following options regarding the resolution limit and the depth of field is/are correct?

An electrochemical cell consists of pure Zn electrode (anode) and a hydrogen electrode (cathode) in a dilute Zn$^{+2}$ solution. The overall reaction is: \[ Zn(s) + 2H^+ \rightarrow H_2 + Zn^{+2} \] If the overall cell potential is +0.690 V, then the value of $\ln \left( \frac{[Zn^{+2}]}{[H^+]^2} \right)$ is ........... (rounded off to two decimal places). Given: Pressure of hydrogen gas = 1 atm; Temperature = 298 K; \[ \frac{RT}{F} = 0.0256 \, V \] Standard reduction potentials: \[ Zn^{+2} + 2e^- \rightarrow Zn (E^0 = -0.762 \, V) \] \[ 2H^+ + 2e^- \rightarrow H_2 (E^0 = 0 \, V) \]

Which of the following statement(s) is/are true for an optical microscope?

Among the 14 Bravais lattices, there is no base-centred cubic unit cell. Which of the following statement(s) is/are true?

TTT diagram of a eutectoid steel is shown below. Match the heat treatment cycle (in Column I) with its microstructure (in Column II).

A screw dislocation in a FCC crystal has Burgers vector of $\frac{a}{2}[110]$, where $a$ is the lattice constant. The possible slip plane(s) is/are:

The tensile true stress ($\sigma$) – true strain ($\varepsilon$) curve follows the Hollomon equation: \[ \sigma = 500 \, \varepsilon^{0.15} \ \text{MPa} \] At the maximum load, the work-hardening rate $\left(\frac{d\sigma}{d\varepsilon}\right)$ is (in MPa):

A student performed X-ray diffraction experiment on a FCC polycrystalline pure metal. The following $\sin^2 \theta$ values were calculated from the diffraction peaks: \[ \sin^2 \theta = 0.136,\; 0.185,\; 0.504,\; 0.544 \] However, the student was negligent and missed noting one of the peaks. Which one of the following Miller indices corresponds to the missing peak?

Match the lattice planes and directions (in Column I) with the corresponding Miller indices (in Column II):

In age-hardening of an aluminium alloy, the purpose of solution treatment followed by quenching is to

The magnetization (M) – magnetic field (H) curves for four different materials are given below. Which one of these materials is most suitable for use as a permanent magnet?

The band gap of a semiconducting material is $\sim 2$ eV. Which one of the following absorption (A) vs. energy (in eV) curves is correct?

Figures (i) and (ii) show a binary phase diagram and the corresponding Gibbs free energy (G) vs. composition ($X_B$) diagram, respectively. Figure (ii) corresponds to which one of the temperatures shown in Figure (i)?