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Unformatted text preview: Jacob Sutker ENGRI 111 Nanotechnology Homework #7 Due: December 4 th , 2006 1. Draw a stress/strain (engineering) curve for a typical metal and a typical ceramic. For the metal also draw the true stress/strain curve. 2. Answer a - k with true or false and explain your answer with a short sentence. (a) Grain boundaries are created when crystals of different orientations are joined together. True It is common that the boundaries are formed from the orientation relationship of neighboring grains in a crystal (b) In a ceramic the tensile stress is 50 % greater than the yield strength. False Since ceramics tend to be porous, the tensile strength is reduced. (c) Metals are not as brittle as ceramics because there are no cracks present. False Ceramics are made of ionic and covalent bonds, both of which do not allow for deformation like metallic bonds. (d) Ceramics are brittle because there are no dislocations present. True Due to the rigid structure of crystalline structures (ceramics), there are no dislocations, so they do not deform.Due to the rigid structure of crystalline structures (ceramics), there are no dislocations, so they do not deform....
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- Fall '07