A series of Ag-Hg and Ag-Pd-Hg phases have been prepared by immersion in mercury and subsequent heat treatment of pure Ag and a series of Ag-Pd alloys. Phase transitions, along with the changes involved in morphology and chemistry, are investigated. Experimental results indicate that when mercury-immersed Ag discs are heat-treatd at 90 °C for 12 h, large (>50 μm) crystals with Ag/Hg atomic ratios close to those of stoichiometric AgHg2 form on the Ag surface. Heat treatment for 36 h causes these crystals to disintegrate into smaller (majority <10 μm) Ag2Hg3 (γ1) crystals. After 60 h, the stoichiometric γ1 crystals further breakdown into even smaller stoichiometric AgHg(β1) crystals. The oft-referenced β1 phase Ag1.1Hg0.9 is not supported in the present study. Addition of Pd to Ag has a dramatic effect on the morphology of the 71 phase. With more addition of Pd, large-faceted and elongated γ1 crystals tend to grow in the midst of smaller matrix γ1 crystals. All three different Pd-containing crystals have (Ag + Pd)/Hg ratios very close to those of the stoichiometric γ1 phase, indicating that added Pd tends to replace Ag, rather than Hg, in the γ1 phase.
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