1. a) Calculate the fraction of atom sites that are vacant for lead at its melting temperature of 327°C (600 K). Assume an energy for vacancy formation of 0.55 eV/atom. b) What would the temperature need to be to create 1/3 the number of vacancies in lead from the percentage at 327°C? (Note: activation energy for the formation of vacancies in lead is 0.55 eV/atom) [20 pts] 2. Table 1 shows atomic radius, crystal structure, electronegativity, and the most common valence are tabulated, for several elements; for those that are nonmetals, only atomic radii are indicated. Table 1 Atomic radius, crystal structure, electronegativity, & the most common valence for several elements Element Crystal Structure Electronegativity 1.8 Valence Ni Atomic Radius (nm) 0.1246 FCC C 0.071 H 0.046 O 0.060 2 2 8 8 8 2 2 2 3 Ag 0.1445 FCC 1.9 Al 0.1431 FCC 1.5 Co 0.1253 HCP 1.8 Cr 0.1249 BCC 1.6 Cu 0.1278 FCC 1.9 Fe 0.1241 BCC 1.8 Pd 0.1376 FCC 2.2 Pt 0.1387 FCC 2.2 Zn 0.1332 HCP 1.6 Which of these elements would you expect to form the following with nickel: (a) A substitutional solid solution having complete solubility (b) A substitutional solid solution of incomplete solubility (c) An interstitial solid solution +1 +3 +2 +3 +2 +2 +2 +2 7 7 7 7 7 7 7 7 7 +2