Question

(A) Explain the atomic origins of elasticity in a metal, polymer and ceramic material. Use atomic force diagram to illustrate your answer.

(B) Explain why powder diffraction is often used as an analytical tool in materials research. What is the information can it provide? ( C)Sketch and label the basic cubic Perovskite structure and briefly explain how it can be used for the following applications: i. Sonar or ultrasound ii. Superconductivity iii. Microwave dielectrics iv. Ionic conduction With regard to a standard tensile test:

(D) Draw a diagram of the apparatus and explain the essential elements. (E) Draw a typical stress strain curve for steel; explain and label the main features. (F) What is the origin of the double yield point?

Answer 1

1. Elastic deformation is reversible that is when load/forces/ consitraints are released the body returns to its original configuration(shape and size) .

2.Elastic deformation can be caused by tension or shear forces .

3.Usually in metal and ceramics elastic deformation is seen at low strains (less than 10^-3).However other materials can be stretched elastically to large strains(few100%).

so elastic deformation should not be small deformation

4.The elastic behaviour of metals and ceramics is usually linear .

   The elastic behaviour of rubber is usually Non-linear .