Constitution of the Al-Ir-Ru system

The Al-Ir-Ru phase diagram was investigated using optical and scanning electron microscopy, energy dispersive X-ray analysis and X-ray diffraction. The results were self-consistent but there was little published literature available for comparison. The B2 phase was found to extend across the ternary, from AlIr to AlRu, with a minimum width of similar to 2 at.% Al within the ternary, Solid solubilities for the extensions of the following binary phases were observed: 10 at.% Ru for similar to Al2.7Ir; 4.6 at.% Ir for similar to Al2Ru; 11.3 at.% Ru for similar to Al13Ir4; and 12 at.% Ir for similar to Ai(13)Ru(4). A previously unreported ternary phase similar to Al53Ir20Ru27 was identified and was shown to form peritectically from BZ, Aluminium was found to be soluble up to similar to 10 at.% in (Ru), and nearly 20 at.% in (Ir). Although the solubility for the other component is high in the Ir-Ru binary, there was a marked decrease within the ternary. Limited solubility ranges were deduced for most of the other phases. Most of the ternary invariant reactions were derived, and a schematic partial liquidus was presented. The hardness measurements of the B2 phase increased with Ir substitution. Other phases identified with high hardnesses were similar to Al2.7Ir, similar to Al53Ir20Ru27 and similar to Al2Ru. (C) 1999 Elsevier Science S.A. All rights reserved.