IGNOU MPHE 25 SOLVED ASSIGNMENT

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MPHE 025 (January 2024 - July 2024) - ENGLISH

Tutor Marked Assignment

MATERIALS SCIENCE

Course Code MPHE-S

Assignment Code PH-SA-25

Note: Attempt all questions. The marks for each question are indicated against t

PART A

1. a) Explain with diagram, how many identical points are created by a roto-inversion operation Anong 3-dion and to-invension operation, which one has higherander? Why?

b) What are glassy alloys Discuss their mechanical prop alance any four technological application of

What are solid solutions Explaithe rules Hume-Rother governing the

2. Explain with the method of growth State advantag over the Cucko

Calculate the mass of phosphorus required to make a silicon crystal with 10 is 2.5 gom and phosphorus has an atomic weight of 30.97 that the segregation coefficient contoughout the growth proces

Describe the importance and conteofpowder metalli

4) What is pitago?What the growth technique State

3. Explain with appropriate diagramopoiected

by Calculate the equilibrioniofacancies copper ca 1000 к Given that melting point of copper 100 and enthalpy of vacancy formation in copper is 120 per mo

c) What is dislocation? Discussion the crystal growth

PART

4. a) Based on the fusion mechanidawhyboardfionis

Explain the Avandofperation based on their assumptions and growth mechani

5. Draw a typical stress curve of material Divarious mechanical strengths and indicate component

b) What is meant by thermal shock spenced by the Howe reduced? State the expression for the shock

Define corrosion in case of materials Discuss the five major factors affecting promoting comson process

6. Explain the phenomenon Giant Magnetoresistance (GR) Give example of the

What are shape memory materials Explain the phase observed in Nially into shape memory phenomenon Discussary to application of shap

What is graphene Descbethebonding grapheneth of graphene nagram

d) What is organiconicontheworking of organic code

MPHE 025 (July 2025) - ENGLISH

Tutor Marked Assignment

MATERIALS SCIENCE

Course Code: MPHE-025

Assignment Code: MPHE-025/TMA/2025

Max. Marks: 100

Note: Attempt all questions. The marks for each question are indicated against it.

PART A

1. a) Explain with diagram, how many identical points are created by a 3 roto-inversion operation. Among 3-fold rotation and 3 roto-inversion operation, which one has higher order? Why?

b) What are glassy alloys? Discuss their mechanical properties vis-à-vis normal metal alloys and ceramic oxide materials. State any four technological applications of glassy alloys.

c) What are solid solutions? Explain the rules (Hume-Rothery) governing the formation of substitutional solid solutions.

2. a) Explain with diagram the float zone method of crystal growth. State its advantages over the Czochralski method.

 b) Calculate the mass of phosphorus required to make a silicon crystal with 107 cm doping density, if the initial melt load of silicon is 50 kg. The density of silicon in the melt is 2.5 g cm³ and phosphorus has an atomic weight of 30.97u. Assume that the segregation coefficient ko=0.35 is constant throughout the growth process.

c) Describe the importance and cost advantages of powder metallurgy in materials processing.

d) What is epitaxial growth? What are the advantages of MBE growth technique? State its applications.

3. a) Explain with appropriate diagrams various point defects observed in solid crystals.

b) Calculate the equilibrium concentration of vacancies in a copper crystal at 1000 K. Given that melting point of copper is 1083°C and enthalpy of vacancy formation in copper is 120 kJ per mole.

c) What is dislocation defect? Discuss its role in the crystal growth.

PART B

4. a) Based on the diffusion mechanisms involved explain why carbon atom diffusion is faster than nickel atom diffusion in iron lattice.

b) What are eutectic phase diagrams? With the help of a schematic diagram for a binary system explain the significance of eutectic point and liquidus, solidus & solvus curves.

c) Explain the Avrami and Johnson-Mehl models of computing phase transformation rates based on their assumptions and growth mechanisms.

5. a) Draw a typical stress-strain curve of a material. Define various mechanical strengths and indicate corresponding deformation regions on this plot.

b) What is meant by "thermal shock" experienced by the materials? How can it be reduced? State the expression for thermal shock resistance (TRS) explaining all the terms involved.

c) Define corrosion in case of materials. Discuss the five major factors affecting /promoting corrosion process.

 

6. a) Explain the phenomena of Colossal Magnetoresistance (CMR) and Giant Magnetoresistance (GMR). Give examples of materials where these effects are observed.

b) What are shape memory materials? Explain the phase transition hysteresis observed in NiTi alloy giving rise to shape memory phenomenon. Discuss any two applications of shape memory materials.

c) What is graphene? Describe the bonding in graphene. Explain the band structure of graphene on E-k diagram.

d) What is organic electronics? Explain the working of an organic diode.

 

 

MPHE 025 (January 2026 - July 2026) - ENGLISH

Tutor Marked Assignment

MATERIALS SCIENCE

Course Code: MPHE-025

Assignment Code: MPHE-025/TMA/2026

Max. Marks: 100

Note: Attempt all questions. The marks for each question are indicated against it.

PART A

1. a) Common types of engineering materials are metals, ceramics, polymers and composites. Compare these four classes on the basis of their composition and any two properties. State one application of each type.

b) With the help of appropriate diagrams describe the possible ways of accommodating the added alloying elements into a pure metal lattice for the following cases:

i) Limited solubility

ii) Good solubility. 

2. a) Explain the difference between chemical vapour deposition and physical vapour deposition. What are the requirements of a material to be used as a holder for the charge in a thermal evaporation system? Mention any three materials used for the purpose. 

b) Given that the density of molten Ge is 5.60 g cm⁻³ calculate the amount of boron required to obtain 10 kg p-type Ge with dopant concentration of 10¹⁷ cm⁻³. Take density of boron = 2.34 g cm⁻³, atomic weight of boron = 10.811 and k₀ = 0.8. 

c) What is green compaction in powder processing? How is the porosity of compacted piece reduced? 

d) How do the interactions between the substrate and adsorbate atoms determine the growth mode of thin films? Describe the various modes of thin film growth. 

3. a) Describe the various methods of creating point defects. Discuss the constructive (positive) effect of dislocations in materials. 

b) Write the symmetries associated with the following 2-D defects:

i) Grain Boundary

ii) Twin Boundary

iii) Stacking Fault 

c) In the inclined crystal plane arrange the following sites in the order of increasing possibility of crystal growth site: terraces, kinks, ledges. 

d) What is F centre defect? Why is there a characteristic absorption energy associated with the F centre? If the F centre absorption energy for CsCl is 2.0 eV, what is its characteristic absorption wavelength? 

PART B

4. a) Explain Fick’s diffusion laws.

b) The enthalpy of vacancy formation in nickel is , and its melting point is . What is the equilibrium vacancy concentration in nickel at ?

c) Explain Lever rule with appropriate diagram.

5. a) Differentiate between Avrami and Johnson-Mehl models of phase transformations.

b) Explain the Austenite to Martensite diffusionless transformation with example.

6. a) Describe the method of performing Vicker’s hardness test with appropriate diagram.

b) Why are the metals opaque to visible light and transparent to x-rays and gamma rays?

c) What is luminescence of a material? Differentiate between fluorescence and phosphorescence.

7. a) Differentiate between ferromagnetism, antiferromagnetism and ferrimagnetism with examples. State the physical significance of magnetic anisotropy.

b) What are Fullerenes? Describe any two applications of Fullerenes.

c) Explain the working of organic LED.

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