An investigation of the phase diagram of the Al–Ir binary system

Al-rich portion of the Ir–Al phase diagram has been investigated with 10 alloys by means of differential thermal analysis, X-ray diffraction, scanning electron microscopy, inductivity coupled plasma spectrometry and electron probe microanalysis. Invariant reactions are observed: L ↔ AlIr + Al2.7Ir, L + Al2.7Ir ↔ Al3Ir, L + Al3Ir ↔ Al13Ir4, L + Al13Ir4 ↔ Al9Ir2. Although the eutectic reaction, L ↔ AlIr + Al2.7Ir, cannot be regarded as definitely established by previous research, it is confirmed in the present research. Liquidus curve has been determined for the first time for Al-rich alloy (Ir ≤ 33.0 at%). The Ir–Al binary phase diagram has been modified based on these experimental observations.