Microprobe analysis of three high-copper amalgams.

Three single-composition, high-copper amalgams were analyzed for the composition of their before- and after-reaction phases. The method used was electron probe microanalysis. The results may be summarized as follows: All alloys consist essentially of Ag3Sn (gamma), Cu3Sn (epsilon), and, in some cases, Ag4Sn (beta). When the original alloy contains higher amounts of Cu, more Cu is found in solution in the Ag3Sn (gamma) and Ag4Sn (beta) phases. The reaction phases in amalgams made from these alloys consist essentially of Ag22Sn Hg27(gamma 1) and Cu6Sn5 (eta'), with no detectable Sn8Hg (gamma 2). When In is present, it is found principally in the Ag3Sn (gamma) and Ag22Sn Hg27(gamma 1) phases, and both the gamma and gamma 1 phases are of different composition than that for the other alloys. When Pd is present, it is found principally in the Cu3Sn (epsilon), Cu6Sn5 (eta'), and Ag22Sn Hg27(gamma 1) phases.