PB-17LI-BISMUTH INTERACTIONS - AN ELECTRICAL-RESISTIVITY STUDY

The reaction of bismuth with Pb-Li alloys has been studied using resis tivity-composition and resistance - temperature measurements to monito r the lithium content of the alloy. The process follows a solution - p recipitation mechansim. The solubility of bismuth was found to be 1.5 x 10(1) mol% (1800 wppm) in Pb-17.04Li (i.e., a Pb-Li alloy containing 17.04 mol% Li) at 723 K and 1.4 x 10(-1) mol% (1800 wppm) in Pb-22.13 Li at 673 K. The Li:Bi ratio in the solid product was found to be 3.07 for Pb-17.04Li, 3.21 for Pb-22.13Li and 3.28 for Pb-17.16Li, indicati ng Li3Bi formation. These observations are interpreted using a phase d iagram developed for the Pb-Bi-Li ternary system from the phase relati onships in the constituent binary systems. It is dominated by the prec ipitation field for Li3Bi which extends from the Bi-Li side almost as far as the Pb-Li side. The dominance of Li3Bi is attributed to its ext reme stability as evidenced by both its high melting point (1418 K) an d free energy of formation (DELTA(f)G-degrees(Li3Bi, c, 723 K) = -212. 8 kJ mol-1).