Experimental investigation of the Al–Y phase diagram

The Al–Y phase diagram has been reinvestigated with 16 key alloys over its whole composition range by means of differential thermal analysis, X-ray diffraction, optical microscopy, and scanning electron microscopy with energy dispersive X-ray techniques. The existence of five intermetallic phases, Al3Y, Al2Y, AlY, Al2Y3, and AlY2, has been confirmed. Al2Y and Al2Y3 melt congruently at 1490 ± 2 and 1105 ± 2 °C, respectively. Al3Y, AlY, and AlY2 are formed via the peritectic reactions L + Al2Y ⇔ Al3Y at 980 ± 2 °C, L + Al2Y ⇔ AlY at 1138 ± 2 °C, and L + Al2Y3 ⇔ AlY2 at 977 ± 2 °C, respectively. Three eutectic reactions L ⇔ (Al) + Al3Y at 637 ± 2 °C, L ⇔ AlY + Al2Y3 at 1081 ± 2 °C, and L ⇔ AlY2 + (αY) at 955 ± 2 °C, are observed. The previously reported Al3Y5, AlY3 compounds were not found. A revised Al–Y phase diagram is presented mainly based on the present experimental results.