Amalgams made from liquid Hg-In

The addition of indium to amalgam appears to reduce the mercury vapour above fillings during setting. In the present work the structure and the physical properties of amalgams with In additions to the mercury up to 30 vol.% have been investigated. No new phase or undissolved In could be detected by X-ray diffraction and scanning electron microscopy studies. Energy dispersive spectroscopy measured 4 at.% In in the γ1-phase of an amalgam with 20 vol.% In added to the mercury. At the same time, the Ag/Hg ratio was substantially increased compared with amalgam having no In addition. The compression strength decreased with increasing In content, and for amalgam with as much as 30 vol.% In added to the mercury, it fell below the minimum requirement of ISO 1559 (Alloys for dental amalgam, International Organization for Standardization, Geneva, 1986). An abrupt drop of the load at the onset of failure and cracks running through the γ1-phase, as well as the η-phase, indicates embrittlement of these phases with increasing In content.