| Materials covered: | Shackelford 4/e Chapters 4 and 7 |
| Date administrated: | 3 February 1998 |
| Time allowed: | 15min |
Answer all questions. Each question carries 1 mark; maximum score is 5 marks.
| 1. | For a thermally activated process,
the materials parameter upon which its rate depends most sensitively is
(b) activation energy; (c) Boltzmann's constant; (d) diffusivity; or (e) defects formation energy ? |
| 2. | Which of the followings is not
a type of defects in a crystal:
(b) screw dislocation; (c) slip system; (d) twin boundary; or (e) surface ? |
| 3. | A polycrystalline sample is examined
in a microscope under 100x magnification. Within a circle of 2.25 inches
in diameter, 21 whole grains and 22 partial grains are counted. What is
the grain-size number of this material?
(b) 4.0; (c) 9.3; (d) 21; or (e) 32 ? |
| 4. | A newly annealed rod of pure
copper is quite flexible, but, after being subjected to stress in everyday
us for some time, it becomes much harder to bend. The reason lies in its:
(b) strain hardening; (c) shear strain; (d) critical resolved shear stress; or (e) Vicker's hardness ? |
| 5. | Among the following five key
mechanical properties that can be measured off the stress-strain characteristic
of a material, which is measured neither as a point along either axes,
nor as a gradient?
(b) yield strength; (c) tensile strength; (d) ductility; or (e) toughness. |
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