Jawaharlal Nehru Technological University Hyderabad
Jawaharlal Nehru Technological University Hyderabad B.Tech II METALLURGY AND MATERIALS SCIENCE Previous Question Paper (March - 2021 - R13)
Answer any five questions. All questions carry equal marks.
Main
Distinguish between grains and grain boundaries.
Answer
Grains are individual, small, single-crystal regions within a polycrystalline material where the atoms are arranged in a regular, repeating lattice pattern. In contrast, grain boundaries are the narrow, disordered transition regions where grains of different crystallographic orientations meet. While grains possess long-range order, grain boundaries are characterized by atomic mismatch, higher energy, and increased reactivity, which act as barriers to dislocation motion.
How the packing efficiency of a crystal structure is defined.
Answer
Packing efficiency, or the Atomic Packing Factor (APF), is defined as the ratio of the volume of atoms in a unit cell to the total volume of the unit cell. It is calculated using the formula:
It represents the fraction of solid space actually occupied by atoms, assuming atoms are hard spheres touching along specific crystallographic directions.
Show that the atomic packing factor of FCC crystal structure is 74%.
Answer
Sign in to view the complete answer paper.
Explain the Gibb’s Phase rule.
Answer
Sign in to view the complete answer paper.
Define allotropy. Give atleast three examples.
Answer
Sign in to view the complete answer paper.
What information can be obtained from an equilibrium diagram?
Answer
Sign in to view the complete answer paper.
Discuss any three methods of construction of phase diagrams. Explain the limitations of each method.
Answer
Sign in to view the complete answer paper.
What are the effects of non-equilibrium cooling?
Answer
Sign in to view the complete answer paper.
Explain how the TTT diagrams are constructed and discuss how the phase transformation takes place at different cooling rates when 0.4%C steel is cooled from austenitic phase to room temperature.
Answer
Sign in to view the complete answer paper.
Discuss how martensitic transformation occurs and explain its characteristics.
Answer
Sign in to view the complete answer paper.
Draw Fe – Fe3C phase diagram and indicate all points, lines and areas along with phase transformation reactions.
Answer
Sign in to view the complete answer paper.
Explain the classification of copper and its alloys.
Answer
Sign in to view the complete answer paper.
Discuss the composition, microstructure, properties and applications of grey cast iron.
Answer
Sign in to view the complete answer paper.
Discuss the classification and applications of Polymers.
Answer
Sign in to view the complete answer paper.
What are crystalline ceramics? Give atleast three examples.
Answer
Sign in to view the complete answer paper.
Distinguish between glasses and cermets.
Answer
Sign in to view the complete answer paper.