Engineering Materials

Choose the correct option:

The BCC structure of Fe-C solid solution is known as

(i) Ferrite
(ii) Pearlite
(iii) Cementite
(iv) Austenite

Choose the correct option:

A solid phase results in a solid plus another solid phase on cooling during

(i) Eutectoid reaction
(ii) Eutectic reaction
(iii) Peritectoid reaction
(iv) Peritectic reaction

Choose the correct option:

Which factor most strongly governs whether a substitutional solid solution forms between metals A and B?

(i) Large electronegativity difference between A and B
(ii) Similar atomic radii and crystal structures with high mutual solubility
(iii) Presence of small interstitial atoms like C or N
(iv) High melting point of the solvent metal alone

Choose the correct option:

The eutectic reaction in a binary alloy system is best described as:

(i) Liquid $\rightarrow$ Solid 1
(ii) Liquid $\rightarrow$ Solid 1 + Solid 2
(iii) Solid 1 $\rightarrow$ Solid 2 + Solid 3
(iv) Liquid + Solid 1 $\rightarrow$ Solid 2

Choose the correct option:

According to Hume Rothery's rule, size of atoms must not differ by more than

(i) 5%
(ii) 35%
(iii) 15%
(iv) 55%

Choose the correct option:

In the Fe-Fe$_3$C equilibrium diagram, ledeburite is:

(i) A mixture of ferrite and austenite
(ii) A single-phase austenitic structure
(iii) Pure cementite
(iv) A eutectic mixture of austenite and cementite

Choose the correct option:

On a two-component solid-liquid phase diagram, a tie line indicates the region where

(i) temperature is constant
(ii) only the solid phase exists
(iii) composition is constant
(iv) only the liquid phase exists

Choose the correct option:

Gibbs phase rule for general system

(i) P + F = C - 1
(ii) P + F = C - 2
(iii) P + F = C + 1
(iv) P + F = C + 2

Define solid solution. Distinguish between substitutional and interstitial solid solutions.

Sketch iron-carbon equilibrium diagram and show the salient points.

Explain what is meant by a solid solution and distinguish between substitutional and interstitial solid solutions.

What is steel? Distinguish between hypoeutectoid and hypereutectoid steels.

With the help of a labelled binary phase diagram, explain how to interpret: Phase fields, liquidus and solidus lines.

Sketch the Fe-Fe$_3$C phase diagram and explain its key features.

Describe eutectic, peritectic, peritectoid and monotectic reactions, clearly stating the phase changes in each case.

A 65wt% Ni - 35wt% Cu alloy is heated to a temperature within the $\alpha$ + liquid phase region. If the composition of the $\alpha$ phase is 70wt% Ni, Determine:

(a) The temperature of the alloy
(b) Composition of liquid phase
(c) The mass fraction of both phases

Write a short note on: Solid Solutions

Write a short note on: Binary Phase Diagrams