List of top Engineering Materials Science Questions

Which one of the following samples of high-purity aluminium (Al) single crystal will plastically yield at the lowest applied load under ambient conditions? Loading axis is along the direction shown in the schematic.

For a glass marginally below its glass transition temperature, which one of the following statements is true?

Refer to the schematic shown. Two dog-bone samples, labelled 1 and 2, of a Cu-alloy are tested under tension at room temperature to points “E” and “P”, respectively. Subsequently, they are unloaded completely and metallographically polished. Brinell hardness testing was performed in the gauge section of the samples. Which one of the following can be inferred about the measured Brinell hardness number (BHN)?

During the ageing of a homogenized Al-Cu alloy (1 to 4 wt.% Cu) below the GP zone solvus, hardness of the alloy:

In an ideal rubber, the primary factor responsible for elasticity up to small strains is

Which one of the following statements is true for an intrinsic semiconductor?

A differential scanning calorimetry (DSC) experiment tracks the heat flow into or out of a system as a function of temperature. If the experiments given in the options below are performed at 1 atmospheric pressure, then in which case will the DSC thermogram exhibit a spike, either upward or downward?

Vickers microhardness (HV) of a ductile material A is higher than another ductile material B. Which of the following is/are true?

The enthalpy required to create an oxygen vacancy in CeO$_2$ is 4 eV. The number of oxygen vacancies present per mole of CeO$_2$ at 1000 K is _________. (Round off to the nearest integer) Given: $N_A = 6.02 \times 10^{23}$ mole$^{-1}$ $k_B = 8.62 \times 10^{-5}$ eV/K

An electrochemical reaction is known to occur at +4.50 V against a Li$^+$/Li reference electrode. The potential of the same reaction against a Zn$^{2+}$/Zn reference electrode is _________. (Round off to two decimal places) Given standard electrode potentials: Li$^+$/Li : $E^\circ = -3.04$ V Zn$^{2+}$/Zn : $E^\circ = -0.76$ V

Number of atoms per unit area of the (110) plane of a body centered cubic crystal, with lattice parameter $a$, is

Match the following materials with their corresponding bonding types.

Match the different transformations/reactions in Column I with the most suitable information in Column II.

A magnet of mass 50 g has a magnetic moment of $ 4.2 \times 10^{-7} \, \text{A m}^2 $. The density of the magnet is 7.2 g/cm³. The intensity of magnetization in A/m is $\underline{\hspace{2cm}}$ (round off to 3 decimal places).

In the context of scanning electron microscopy, match the information in Column I with the most appropriate information in Column II.

Match the heat treatment processes given in Column I with the most suitable outcomes in Column II.

A co-joined cross-ply laminate composite, as shown in the figure, is distorted upon heating. What are the resultant shapes of edges XY and YZ?

Fe - 10 atom % C austenite (fcc), having no Fe vacancies, has a lattice parameter of 4 Å. The density of austenite in g/cm³ is $\underline{\hspace{2cm}}$ (round off to 2 decimal places).

An element transforms from $ \alpha $ to $ \beta $ at 773 K and 1 atm pressure with 912 J mol$^{-1}$ as enthalpy of transformation. The molar volumes of $ \alpha $ and $ \beta $ phases are 7.377 cm³ and 7.317 cm³, respectively. Assume that the difference in molar volumes of $ \alpha $ and $ \beta $ is independent of pressure. The pressure (in atm) required for $ \alpha $ to $ \beta $ transformation to occur at 723 K is $\underline{\hspace{2cm}}$ (round off to nearest integer).

When a metal (M) is immersed in de-aerated acid electrolyte, it polarizes anodically by 0.4 V. The M/M$^{n+}$ exchange current density is $ 10^{-5} \, \text{A m}^{-2} $ and Tafel slope is 0.1 V/decade for the anodic reaction. Assume that corrosion is uniform and anodic and cathodic reactions are under activation control. The rate of metal dissolution in A m\textsuperscript{-2 is $\underline{\hspace{2cm}}$ (round off to 1 decimal place).}

The drift mobility of electron in an n-type Si crystal doped with $ 10^{16} \, \text{cm}^{-3} $ phosphorous atoms is $\underline{\hspace{1cm}}$ (round off to nearest integer).

During heating, Ti undergoes allotropic transformation from hcp to bcc at 882 °C. The percent volume change accompanying this transformation is $\underline{\hspace{2cm}}$ (round off to 1 decimal place).

A binary A-B alloy has $ \alpha $ and $ \beta $ phases at equilibrium. The ratio of weight percentages (wt.%) of $ \alpha $ to $ \beta $ is 4. The wt.% of A in $ \alpha $ and $ \beta $ phases is 70 and 20, respectively. The wt.% of B in the alloy is $\underline{\hspace{2cm}}$ (round off to nearest integer).

At 1000 K, the linear thermal expansion coefficients of graphite, parallel and perpendicular to the graphite layers, are $ 0.8 \times 10^{-6} \, \text{K}^{-1} $ and $ 29 \times 10^{-6} \, \text{K}^{-1} $, respectively. The percentage increase in the volume of graphite when heated from 900 K to 1100 K is $\underline{\hspace{2cm}}$ (round off to 2 decimal places).

A certain ceramic has a theoretical density and sintered density of $ 6.76 \, \text{g/cm}^3 $ and $ 6.60 \, \text{g/cm}^3 $, respectively. The green compact has 18 volume percent porosity. For a sintered cube of side 2 cm, the required side of the cubic green compact in cm is $\underline{\hspace{2cm}}$ (round off to 2 decimal places).