MATLS 1M03 Chapter 3: chapter 3.pdf

• School: McMaster University
• Department: Materials Science and Engineering
• Course: MATLS 1M03
• Professor: Hatem Zurob

Document Summary

1: crystalline material: atoms arrange into a periodic array (cid:4666)repetitive three dimensional pattern/ arrangement of atoms lattice structure(cid:4667). Repeated pattern called crystal lattice: non crystalline / amorphous material:do not crystallize, i. e. there is no long range atomic order, crystal structure: manner in which atoms, ions or molecules are spatially arranged, many possible structures defined by. Crystalline usually (cid:4666)e. g. steel, brass(cid:4667) often (cid:4666)e. g. alumina(cid:4667) never (cid:4666) crystalline polymers always partly amorphous(cid:4667) metals ceramics polymers. Amorphous rarely (cid:4666)e. g. metallic glass(cid:4667) often (cid:4666)e. g. soda glass(cid:4667) usually (cid:4666)e. g. polyethylene(cid:4667) Mixed never often (cid:4666)e. g. silicon nitride(cid:4667) sometimes (cid:4666)e. g. nylon(cid:4667) Each circle occupies an "equivalent area" of 4r2, because no other sphere can use this area. "equivalent area", making this a more efficient packing system. Area (cid:3404) (cid:4666) 3/2(cid:4667)(cid:4666)2r(cid:4667)2(cid:3404) 3. 464 r2: hiscocks, 2003. 7: the curve of the watchglass pushes the spheres together. Equivalent to a bonding force: 2 d close packing occupies the smallest area and lowers the overall energy.