The reaction zone around experimental amalgam alloy particles of Ag-Cu eutectic composition

An electron microprobe was used to investigate the composition and microstructure of the reaction zone occurring around experimental particles of approximately Ag-Cu eutectic composition in two experimental dental amalgams. This study formed the basis for the examination, described in a subsequent paper, of the reaction zones in several commercially available amalgams. Techniques of phase composition analysis were further developed in order to identify and quantify the component phases in the regions of the reaction zone. The clumped, outer, more darkly shaded region of the zone contained predominantly eta 1 (Cu6Sn5) phase. The inner, more lightly shaded region of the reaction zone was found to contain substantial quantities of eta 1, gamma 1, a Cu-Hg phase and a Ag-Cu component.