A furnace wall consists of four layers of different materials, M1, M2, M3 and M4. If the layers are of equal thickness and the steady state temperature profiles is as shown below, then the material with the lowest thermal conductivity is <img src="/images/question-image/metallurgical-engineering/miscellaneous-in-metallurgy/1684344797-M2-B-19-27.PNG" title="Miscellaneous in Metallurgy mcq question image" alt="Miscellaneous in Metallurgy mcq question image">

A furnace wall is made of three materials (I, II and III) of equal thickness and having thermal conductivity k₁ k₂ and k₃ respectively. The steady state temperature profile inside each material is shown in the figure. Thermal conductivities of the materials will vary as
Miscellaneous in Metallurgy mcq question image

Miscellaneous in Metallurgy mcq question image

A

k₁ > k₂ > k₃

B

k₂ > k₁ > k₃

C

k₃ > k₁ > k₂

D

k₃ > k₂ > k₁

A furnace wall consists of two layers. The inside layer of 450 mm is made of light weight bricks of thermal conductivity IW/m.K and outside layer of 900 mm is made of refractory of thermal conductivity 2W/m.K. The hot face of the inside layer is at temperature 1300 K and the cold face of the outer layer is at 400 K. The temperature at the interface between the two layers is . . . . . . . . K.

A

1000

B

850

C

700

D

600

Thin layer of material B (of total amount m) is plated on the end faces of two long rods of material A. These are then joined together on the plated side (see the figure below) and heated to a high temperature. Assuming the diffusion coefficient of B in A is D, the composition profile CB along the rod axis x after a time t is described by
Introduction to Metallurgy mcq question image

Introduction to Metallurgy mcq question image

A

$${C_B} = \frac{m}{{2\sqrt {\pi Dt} }}\exp \left$$

B

$${C_B} = \frac{m}{{2\sqrt {\pi Dt} }}erf\left$$

C

$${C_B} = \frac{m}{{2\sqrt {\pi Dt} }}\left$$

D

$${C_B} = \frac{m}{{2\sqrt {\pi Dt} }}t$$

A wall has two layers of materials A and B; each made of a different material. Both the layers have the same thickness. The thermal conductivity of materialA is twice that of B. Under the equilibrium, the temperature difference across the wall is 36°C. The temperature difference across the layer A is __________ °C.

A

6

B

12

C

18

D

24

An alloy of overall composition, X_B = 0.7 was equilibrated at temperature T₁. 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 . . . . . . . .
Physical Metallurgy mcq question image

A

0.05

B

0.10

C

0.50

D

0.85

A furnace is made of a refractory brick wall of thickness 0.5 metre and thermal conductivity 0.7 W/m.°K For the same temperature drop and heat loss, this refractory wall can be replaced by a layer of diatomaceous earth of thermal conductivity 0.14 W/m.K and thickness __________ metre.

A

0.01

B

0.1

C

0.25

D

0.5

A simplified energy band-diagram of an intrinsic semiconductor at thermal equilibrium (300 K) is shown. In the accompanying table, which one of the four cloumns correctly represents the listed parameters? Assume same effective mass for electrons and holes.
Physics of Metals in Metallurgy mcq question image

Physics of Metals in Metallurgy mcq question image

A

Parameter	Energy-difference
Parameter	Column 1	Column 2	Column 3	Column 4
Band-gap	ΔE₂	ΔE₁	ΔE₂	ΔE₁
Electron affinity	$$\frac{{\Delta {E_1}}}{2}$$	ΔE₂ - ΔE₁	$$\frac{{\Delta {E_2}}}{2}$$	ΔE₂ - $$\left( {\frac{{\Delta {E_1}}}{2}} \right)$$
Work function	ΔE₁ + ΔE₂	ΔE₂ - $$\left( {\frac{{\Delta {E_1}}}{2}} \right)$$	ΔE₁ - $$\frac{{\Delta {E_2}}}{2}$$	ΔE₂ + $$\left( {\frac{{\Delta {E_1}}}{2}} \right)$$

Column 1

B

Column 2

C

Column 3

D

Column 4

A composite flat wall of a furnace is made of two materials 'A' and 'B'. The thermal conductivity of 'A' is twice of that of material 'B', while the thickness of layer of 'A' is half that of B. If the temperature at the two sides of the wall are 400 and 1200°K, then the temperature drop (in °K) across the layer of material 'A' is

A

125

B

133

C

150

D

160

The diffusion couple shown below is made from two A-B alloys. The initial compositions of the two alloys are indicated in the diagram. The centreline is at x = 0. The couple is held at an elevated temperature for 40 hours. Diffusivity; D = 3 × 10^-11 m^-2 s^-1. Assume the diffusion couple to be infinitely long.
Physical Metallurgy mcq question image

Which of the parameters give the composition profile in the following form?
$$C\left( {x,t} \right) + {c_1} + {c_2}\,erf\left( {\frac{1}{{2\sqrt {Dt} }}} \right)$$

A

c₁ = 0.45, c₂ = 0.05

B

c₁ = 0.5, c₂ = 0.4

C

c₁ = -0.05, c₂ = 0.45

D

c₁ = 0.1, c₂ = 0.9

Match the heat treatment for an eutectoid steel shown in the TTT diagram below (as P, Q, R and S) with the resulting microstructure listed below:
1. Fine pearlite
2. martensite
3. Bainite
4. Coarse pearlite
Physical Metallurgy mcq question image

A

P-1, Q-2, R-4, S-3

B

P-4, Q-1, R-3, S-2

C

P-2, Q-1, R-3, S-4

D

P-1, Q-4, R-3. S-2

A furnace wall consists of four layers of different materials, M₁, M₂, M₃ and M₄. If the layers are of equal thickness and the steady state temperature profiles is as shown below, then the material with the lowest thermal conductivity is

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