MATS 3011 Lecture Notes - Intermetallic, Diamond Cubic, Tetragonal Crystal System
Document Summary
O-d defects: vacancies, interstitials, substitutional defects: foreign atom substituted in place of host atom. Depends on how big the atom substituting it is; identity matters. If it"s the same size, could substitute a lot or as much as you want. Cu and ni alone and pure both = fcc. Electronegativities: for cu, it"s 1. 9 and for ni its 1. 8 --> close enough (no hard and fast rule for how much electronegativity difference allowed) Used for: corrosion resistant coatings, underwater structure (not for weight/loads, but for tanks, condensers) Example 2: pb-sn (used in solder, melting point reduced when you mix them) Pb = fcc, sn = tetragonal --> not going to mix at all compositions. Si has 4 valence electrons --> wants 4 bonds w/ other si. P has an extra electron than si so when it goes in and replaces si, there"s an extra electron not bound anywhere --> # p atoms put in = # electrons put in.
