【正文】
Chapter Three Structures of Metals and Ceramics Lecturer: Shenhua SONG ? Unit cells ? Metallic crystal structures ? Ceramic crystal structures ? Crystal systems ? Crystallographic directions and planes Unit cells Small repeat atom groups in a crystal structure Representation of a unit cell: (a) hardsphere model。 (b) reduced hardsphere model。 (c) an aggregate of many atoms Metallic crystal structures (1) Three major types: 1) Facecentered cubic (FCC) crystal structures 2) Bodycentered cubic (BCC) crystal structures 3) Hexagonal closepacked (HCP) crystal structures Metallic crystal structures (2) 1) Facecentered cubic (FCC) crystal structure 2R a 24 aR ?42aR ? Each unit cell contains 4 atoms Metallic cry