What is the advantage of nitriding? Select all correct answers.     Some complex components can be nitride without difficulty.     Better wear resistance.     Better fatigue resistance.     The cheapest method of case hardening.

a) On the atomic level, what causes strain hardening?   b) Explain the difference between engineering stress and true stress. Under tension, which one is greater, and why?

You have been given the following test sample data following mechanical testing of 15 test pieces of a transformation toughened zirconia. What is the Weibull modulus of this material? Would you advise the use of this material over one with a Weibull Modulus of 25.4 and a mean failure stress of 235 MPa, if you anticipate that the peak stress on the material could be 220 MPa? (Since this question has two parts, you must select the two correct options from the list below) Test Sample Failure Stress (MPa) 1 255 2 271 3 260 4 223 5 257 6. 267 7 242 8 230 9. 245 10 225 11 254 12 236 13 238 14 251 15 264 O a. 27.3 O b. 4.5 O c. 6.9 O d. Yes е. 15.2 O f. 18.3 O g. No O O O O O O O

(a) Describe the major difference between toughness and fracture toughness. (b) Explain what fatigue and creep are.

A fracture surface of a metal matrix composite (nickel with silicon carbide fibres) is investigated with a Scanning Electron Microscope (SEM). Questions: a. Which signals can you use to make an image of the sample? b. Which signal do you prefer to observe the fracture surface? c. How can you discriminate between the matrix and the fibres? d. How can you increase the magnification to observe a detail with the SEM?

The minimum yield strength for iron with an average grain size of 6x10^-2 mm is 135 MPa, this increases to 260 MPa when the average grain size is reduced to 8x10^-3 mm.What must the average grain size be to achieve a yield strength of 205 MPa.

Name some properties of materials. How do you define these properties? Where do they come from?

Thermal shock, a situation in which a hot object is suddenly exposed to a colder temperature, can often lead to the failure of many ceramic and polymer materials.a) Describe how thermal shock leads to fracture of a material even when its dimensions are not physically constrained.b) Explain why thermal shock is not typically a problem for most metals

8. Design Problem: A material is needed to support a hanging sculpture with an overall tensile load of 800 N. It is important that the material not undergo any permanent deformation under this load and must have minimum volume/diameter. Using a circular rod, design structural components using your data for each of the three materials. Which material would you choose for the application and why? If the requirement was minimum weight, rather than minimum volume, which material would you use? Show sample calculations.

Can the yield point of material be increased by strain hardening?