Progress in splat-cooling of dental alloys

Improved techniques in preparing and sizing dental alloy powders containing Ag, Sn, and Cu have led to amalgams with higher strengths and less spread in dimensional change but very poor shelf life. Since maximum strengths occurred for amalgams containing about 15% more Sn than previously reported, and consequently presumably more of the weak gamma2 phase, the higher strengths are difficult to understand. The poor shelf life may be explained by oxidation of the highly reactive splat-cooled alloy or possibly by the existence of highly reactive metastable phases which transform fairly rapidly to the less reactive equilibrium ones.