Material Science & Metallurgy - Jun 2014

Mechanical Engg. (Semester 3)

TOTAL MARKS: 100
TOTAL TIME: 3 HOURS (1) Question 1 is compulsory.
(2) Attempt any four from the remaining questions.
(3) Assume data wherever required.
(4) Figures to the right indicate full marks. 1 (a) Define the following lattice;
Unitcell.
Space lattice.
Atomic packing factor.
Coordination number.(4 marks) 1 (b) Calculate the volume of the zinc crystal structure unit cell by using the following data:pure zinc has the HCP crystal structure with lattice constant a-o.2665nm and c=0.4947,_nm(4 marks) 1 (c) State and explain Fick first law of diffusion (4 marks) 1 (d) What do you mean by crystaline impersion ?Expalin brifly point and scalar /line defects (8 marks) 2 (a) Compare the engineering stress and strain with the true stress and stress for the tensile test a low carbon steel that has the following test values :
Load applied to seciaman =75kN
initial diameter of specimen under 75kN load -12mm(4 marks) 2 (b) Derive the expresion for critically resolved sher stress (CRSS)(4 marks) 2 (c) Describe the dislocation mcanism that enables a metal to be plastically deformed within fracture (6 marks) 2 (d) What do you mean by linear and nonlinear elastic propertise of a material ?Explain any four propertis e(6 marks) 3 (a) Define creep and explain a typical curve(6 marks) 3 (b) what is frature ?state the difference between ductile and brittle fracture (8 marks) 3 (c) State the factor that affect the figure strength of a metal. Explain them briefly.(6 marks) 4 (a) state and explain Gibbs phase rule(4 marks) 4 (b) Explain homogenous nucleation .discuss the significance of critical radius of nuclci(8 marks) 4 (c) What is a solid solution?with suitable example ,explain the different types of solid solution(8 marks) 5 (a) Define :
A phase in a material
A phase diagram(2 marks) 5 (b) Derive the level rule for the binary phase diagrame of two metals A and B completely soluble in each other(4 marks) 5 (c) write the equation for the following invarient reaction;enteric,pericctic,monoteric entecoid and periticoid .How many degree of freedom exist at invariant reaction points in binary phase diagram?(6 marks) 5 (d) Draw nearly Iron-carbon phase diagram and mark on it all sailent tempreture composition ,and phases(8 marks) 6 (a) Explain the steps to construct TTT diagram.draw a labcled sketch of TTT diagram for an cuteetoid steel(10 marks) 6 (b) with neat diagrams ,explain briefly austempering an d martempering hear treatement process (10 marks) 7 (a) Discuss briefly about of alloying elements on properties of steel (10 marks) 7 (b) Explain with phase diagram modification of Al-Si Alloys(5 marks) 7 (c) Write a note on spherodial Graphite (SG)iron (5 marks) 8 (a) (10 marks) 8 (b) Explain with a neat sketch production of MMC by using powder mctalyurgy process(10 marks)