Physical Metallurgy — Part 2 MCQs with Explanations

P-2, Q-1, R-3, S-4 is the correct answer to “Match the names in Group 1 with invarient reactions in binary phase diagram in Group 2 . Group 1 Group 2 P. Eutectic 1. S 1 = S 2 + S 3 Q. Eutectoid 2. L = S 1 + S 2 R. Peritectoid 3. L 1 = L 2 + S S. Monotectic 4. S 1 + S 2 = S 3”. This question is standard in competitive examination syllabi for Physical Metallurgy.

2 is the correct answer to “Assume that Sievert's law holds for solubility of hydrogen dissolved in a thin metal foil. If the partial pressure of hydrogen in contact with the foil is increased by a factor of 4, the solubility increases by a factor of”. This question is standard in competitive examination syllabi for Physical Metallurgy.

P-2, Q-3, R-2, S-1 is the correct answer to “Match the heat treatment processes of steel in Group 1 with the microstructural features in Group 2 . Group 1 Group 2 P. Quenching 1. Bainite Q. Maraging 2. Martensite R. Tempering 3. Internietallic precipitates S. Austempering 4. Epsilon carbide”. This question is standard in competitive examination syllabi for Physical Metallurgy.

0 is the correct answer to “The free energy change during melting of ice at 0°C is equal to”. This question is standard in competitive examination syllabi for Physical Metallurgy.

210°C is the correct answer to “At which temperature, cementite changes ferromagnetic to paramagnetic character in iron carbon diagram”. This question is standard in competitive examination syllabi for Physical Metallurgy.

More is the correct answer to “The elastic strain energy of a unit length of an edge dislocation as compared to that of a screw dislocation is”. This question is standard in competitive examination syllabi for Physical Metallurgy.

L + α = β is the correct answer to “The peritectic reaction in binary systems is given by”. This question is standard in competitive examination syllabi for Physical Metallurgy.

0.36 is the correct answer to “The critical nucleus size (in mm) when copper melt is under-cooled by 100K is Given data: Melting point: 1356 K Density: 8900 kg.m -3 Solid-liquid interfacial energy: 0.5 Jm -2 Latent heat of freezing: 13000 J. mol -1 Molar volume: 7 × 10 -6 m 3 mol -1”. This question is standard in competitive examination syllabi for Physical Metallurgy.

Symmetry of the product is different from the parent phase but the unit cell volume increases is the correct answer to “Which of the following is true for martensitic transformation in steels”. This question is standard in competitive examination syllabi for Physical Metallurgy.

33% is the correct answer to “If the interfacial energy is increase by 10%, the homogeneous nucleation barrier for a spherical particle increases by”. This question is standard in competitive examination syllabi for Physical Metallurgy.

1 + exp (-α2t) is the correct answer to “A number of solid state phase transformations follow a sigmoidal pattern. In these eases, at any time the fraction transformed can be expressed as”. This question is standard in competitive examination syllabi for Physical Metallurgy.

Q, R is the correct answer to “From an alloy, two specimens are machined and tested separately under tension and compression. The engineering stress-strain curves as well as the true stress-true strain curves for tension and compression are plotted in the same diagram. Identify the correct statements: P. The engineering stress-strain curves in tension and compression are identical. Q. The true stress-true strain curve in compression is lower than the true stresstrue strain curve in tension due to Bauschinger effect. R. The true stress-true strain curve in tension is above the corresponding engineering stress-strain, curve. S. The true stress-true strain curve in tension and compression are identical.”. This question is standard in competitive examination syllabi for Physical Metallurgy.

Cr is the correct answer to “Which one of the following is a ferrite stabiliser in steels”. This question is standard in competitive examination syllabi for Physical Metallurgy.

size factor is the correct answer to “In Cu-Al phase diagram, the solubility of Al in Cu at room temperature is about 10% and that of Cu in Al is less than 1%. The Hume-Rothery rule that justifies this difference is”. This question is standard in competitive examination syllabi for Physical Metallurgy.

Elastic modulus is the correct answer to “The property of a material that cannot be significantly changed by heat treatment is”. This question is standard in competitive examination syllabi for Physical Metallurgy.

47.5 is the correct answer to “A binary phase diagram of components P and Q displays an eutectoid reaction with terminal solid solutions a on the P rich side and β on the Q rich side. At the eutectoid temperature, the solubilities of Q in a and β are 5 and 90 wt% respectively. The densities of α and β phases are 9.5 and 2.49 gm/cm 3 respectively. At the eutectoid point, the alloy has α and β in the weight ratio 1 : 1. The eutectoid point occurs at composition . . . . . . . . wt % Q.”. This question is standard in competitive examination syllabi for Physical Metallurgy.

P-3, Q-4, R-1, S-2 is the correct answer to “Match the elements is Group I with their corresponding crystal structures in Group II . Group I Group II P. Tungsten 1. HCP Q. Nickel 2. Simple cubic R. Magnesium 3. BCC S. Polonium 4. FCC”. This question is standard in competitive examination syllabi for Physical Metallurgy.

P-3, Q-2, R-4, S-1 is the correct answer to “Match each phase in Group 1 with a description in Group 2 . Group 1 Group 2 P. E-carbide 1. A three component eutectic of iron, iron carbide, iron phosphate found in cast iron Q. Sigma phase 2. An embrittling compound found in ferritic stainless steel R. E-ferrite 3. Obtained on tempering of hardened steels S. Steadite 4. Responsible for causing the weld deposit on austenitic stainless steels to be slightly magnetic”. This question is standard in competitive examination syllabi for Physical Metallurgy.

9.16 is the correct answer to “A liquid phase sintered SiC-Ni composite has a solid-solid grain boundary energy (γ SiC-SiC ) of 0.80 J.M -2 and a solid-liquid (γ SiC-SiC ) interfacial energy of 0.45 J.m -2 . For a SiC grain size of 20 μm, the average interparticle (SiC-SiC) neck size (in μm) is:”. This question is standard in competitive examination syllabi for Physical Metallurgy.

0 is the correct answer to “If the slip direction is at right angle to the tensile axis, then the value of critical resolve shear stress is”. This question is standard in competitive examination syllabi for Physical Metallurgy.

low stacking fault energy is the correct answer to “Dislocation cross-slip is difficult in those materials which have”. This question is standard in competitive examination syllabi for Physical Metallurgy.

Invariant is the correct answer to “The number of components is 2, the number of phases are 3 and degrees of freedom are 0. Then which of the following equilibrium is it”. This question is standard in competitive examination syllabi for Physical Metallurgy.

160 is the correct answer to “In the hypothetical phase diagram, the melting point of each pure component is. 1000 K and the eutectic temperature is 800 K. The eutectic is located at the equi-atomic composition. The maximum solid solubility in α-phase is given by the mole fraction, Ne = 0.1. The freezing range (in K) of the alloy with composition, Ne = 0.1 is”. This question is standard in competitive examination syllabi for Physical Metallurgy.

First increases and then decreases is the correct answer to “With the increase in the degree of supercooling, the growth rate of a nucleus follows which one of the following trends”. This question is standard in competitive examination syllabi for Physical Metallurgy.

P-3, Q-2, R-4, S-1 is the correct answer to “Match the heat treatment process in Group I with resultant microstructure Group II . Group I Group II P. Martempering 1. Coarse pearlite Q. Normalising 2. Fine pearlite R. Sub-critical annealing for long time 3. Tempered martensite S. Full annealing 4. Spheroidised cementite in the matrix of ferrite”. This question is standard in competitive examination syllabi for Physical Metallurgy.

P-1, Q-2, R-4, S-3 is the correct answer to “Match the items in Group1 with those in Group2 . Group 1 Group 2 P. Fatigue 1. Cracking at extrusions and intrusions Q. Hall-petch equation 2. Dislocation pile up R. Creep 3. Slip and twinning S. Plastic deformation 4. Grain boundary sliding 5. Angle of grain boundary 6. Young's modulus”. This question is standard in competitive examination syllabi for Physical Metallurgy.

a is true but r is false is the correct answer to “Determine the correctness or otherwise of the following Assertion (a) and Reason (r) . Assertion (a): Peak aging time for an Al-4 wt.% Cu alloy is indicated by a maximum in the hardness. Reason (r): The maximum volume fraction of the θ precipitates is formed at the peak aging time.”. This question is standard in competitive examination syllabi for Physical Metallurgy.

500 is the correct answer to “The stress required for Orowon dislocation bypass is 200 MPa in an alloy when the interprecipitate spacing is 500 nm. In the same alloy, if the inter-precipitate spacing is reduced to 200 nm, the stress required (in MPa) is”. This question is standard in competitive examination syllabi for Physical Metallurgy.

Vacancy is the correct answer to “The self diffusion in FCC metals occurs by one of the following mechanisms.”. This question is standard in competitive examination syllabi for Physical Metallurgy.

β phase only is the correct answer to “A binary alloy system A-B shows the peritectic reaction, L + α (⟶β). An alloy of the peritectic composition when cooled under natural cooling conditions will show coring in”. This question is standard in competitive examination syllabi for Physical Metallurgy.

only in iron-based alloys is the correct answer to “It is possible to form martensite”. This question is standard in competitive examination syllabi for Physical Metallurgy.

P-2, Q-3, R-4, S-1 is the correct answer to “The following reactions are written such that the forward reaction occurs during cooling. Match the reactions to their names. Group-I Group-II P. Y = α + β 1. peritectoid Q. L+ α = β 2. Eutectoid R. L 1 = L 2 + α 3. Peritectic S. α + β = Y 4. Monotectic”. This question is standard in competitive examination syllabi for Physical Metallurgy.

P-3, Q-1, R-2, S-4 is the correct answer to “Match the associated primary change in Group 2 with the corresponding phenomenon in Group 1 . Group 1 Group 2 P. Recovery 1. change in dislocation density Q. Recrystallisation 2. change in the shape of a phase R. Malleabilising 3. change in vacancy concentration S. Texture 4. change in grain orientation”. This question is standard in competitive examination syllabi for Physical Metallurgy.

0.10 is the correct answer to “An alloy of overall composition, X B = 0.7 was equilibrated at temperature T 1 . Microstructural analysis showed two phases, (α and β, and that the phase fraction of β was 0.75. Given that the equilibrium composition of β at Ti is 0.9 as shown in the phase diagram below, the maximum solubility of B in α (in mole fraction) at this temperature is . . . . . . . .”. This question is standard in competitive examination syllabi for Physical Metallurgy.

Q, R, S is the correct answer to “According to Griffith theory, which of the following are true for the fracture stress in a brittle material? P. Increases with increasing surface energy Q. Decreases with increasing elastic modulus R. Decreases with increasing length of pre-existing crack S. Decreases with increasing number of pre-existing cracks of same size”. This question is standard in competitive examination syllabi for Physical Metallurgy.

P-4, Q-3, R-1, S-2 is the correct answer to “Match the following strengthening methods (Group I) in metallic alloys with typical mechanisms responsible (Group II) for them. Group I Group II P. Grain size strengthening 1. Orowan looping Q. Work hardening 2. Suzuki interaction R. Dispersion strengthening 3. Lomer-Cottrell-barrier S. Solid solution hardening 4. Dislocation pile up at grain boundaries”. This question is standard in competitive examination syllabi for Physical Metallurgy.

Reducing carbon content is the correct answer to “Which one of the following can avoid weld decay of austenitic stainless steels”. This question is standard in competitive examination syllabi for Physical Metallurgy.

low or medium carbon steel is the correct answer to “Lath martensitic microstructure we can see in”. This question is standard in competitive examination syllabi for Physical Metallurgy.

Finer the initial grain size, higher is the recrystallization temperature is the correct answer to “Regarding recrystalisation, which one of the following statements is not correct”. This question is standard in competitive examination syllabi for Physical Metallurgy.

Czochralski method is the correct answer to “Which of the following manufacturing processes is not used for producing fine grained metals”. This question is standard in competitive examination syllabi for Physical Metallurgy.