Experimental investigation of the Al–Y phase diagram

Abstract

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, Al 3Y, Al 2Y, AlY, Al 2Y 3, and AlY 2, has been confirmed. Al 2Y and Al 2Y 3 melt congruently at 1490 ± 2 and 1105 ± 2 °C, respectively. Al 3Y, AlY, and AlY 2 are formed via the peritectic reactions L + Al 2Y ⇔ Al 3Y at 980 ± 2 °C, L + Al 2Y ⇔ AlY at 1138 ± 2 °C, and L + Al 2Y 3 ⇔ AlY 2 at 977 ± 2 °C, respectively. Three eutectic reactions L ⇔ (Al) + Al 3Y at 637 ± 2 °C, L ⇔ AlY + Al 2Y 3 at 1081 ± 2 °C, and L ⇔ AlY 2 + (αY) at 955 ± 2 °C, are observed. The previously reported Al 3Y 5, AlY 3 compounds were not found. A revised Al–Y phase diagram is presented mainly based on the present experimental results.