1 (a) Briefly explain the difference among edge,screw,and mixed dislocations in terms of the relative orientation line and Burgers vector.
(b) For each of edge,screw,and mixed dislocation,cite the relationship between burgers vector and the direction line motion.
2 Based on our textbook and what we have learnt,cite not less than four techniques to strengthen and harden aluminum metal in aviation?
3 Briefly describe types of short-circuit diffusion and its contribution tothe overall diffusion flux.
4 (a) For each of edge,screw,and mixed dislocation,cite the relationship between the direction of the applied shear stress and the direction of dislocation line motion.
(b) Cite one reason why ceramic materials are,in general,harder yet more brittle than metals.
5 Describe and explain solid-solution strengthening for substitutional impurity atoms(smaller or larger than host atoms)in terms of lattice strain interactions with dislocations.
6 (a) Suppose that Li2O is added as an impurity to MgO,If the Li+ substitutes for Mg2+,what kind of vacancies would you expect to form?How many of these vacancies are created for every Li+ added?
(b) Suppose that MgCl2 is added asimpurity to MgO.If the Cl- substitutes for O2-,what kind of vacancies would you expect to form?How many of these vacancies are created for every Cl- added?