The Effect of Temperature and Pressure on Ag-Sn-Hg Alloys

Abstract

Studies have been conducted to evaluate the influence of temperature and pressure on Hg loss and structural transitions in Ag-Sn-Hg alloys containing varying amounts of Sn. Hg loss and structural transitions in the alloys that were subjected to heat (100°C) and pressure (193 MN/m²) show that Sn atoms from the γ_z (Sn_7–8Hg) phase can be forced into and accommodated by the γ₁ (Ag_zHg₃) and β₁ (AgHg) lattices, leaving no γ₂ as a unique phase in the alloy. Samples heated to 100°C at atmospheric pressure exhibited virtually no Hg loss for the Sn-containing alloys. However, in the absence of applied pressure, the γ₁ amalgam was seen to transform to the β₁ and γ_Z phases. This implies that Hg liberated by γ₁ decomposition is not given off by the sample as free Hg but reacts with excess Ag₃ to force a self-perpetuating reaction.