Journal Archive

Platinum Metals Rev., 1966, 10, (1), 8

The Reactions of Iridium with Boron, Phosphorus and Silicon

  • A. S. D.

Some recent high temperature metallography by Dr Reinacher, of Degussa (Metall, 1965, 19, (7), 707–711), indicates that the alloys of iridium with boron, phosphorus and silicon have eutectics melting at temperatures considerably higher than those of the corresponding platinum and palladium systems. Iridium containing approximately 1.5 per cent by weight of boron begins to melt at 1046°C, the eutectic being formed between IrB and an iridium solid solution of unknown composition. At the iridium rich end of the phosphorus-iridium diagram melting occurs at 1262°C when the compound Ir2P reacts with what appears to be almost pure iridium. The first compound encountered when silicon is added to iridium is Ir3Si. With the iridium solid solution this forms a eutectic melting at 1470°C.

Although the silicides, phosphides and borides of iridium have all been previously studied and identified, little attention has hitherto been paid to the melting point relationships in these three binary systems. The present high temperature determinations help to explain what analytical chemists have already known for a long time. Certain difficult fusions which would completely destroy platinum crucibles can be successfully accomplished in iridium, and this paper should do much to encourage the further use of iridium in some types of chemical work.

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