Eutectic Composition in the Pseudobinary of Y ₄ Al ₂ O ₉ and Y ₂ O ₃

Abstract

The eutectic composition between Y 4 Al 2 O 9 and Y 2 O 3 was determined using electron probe microanalysis (EPMA) on directionally solidified specimens with hypo‐ and hypereutectic compositions. The microstructures of the specimens as a function of composition differ considerably with small deviation from the eutectic composition (70.5 mol% Y 2 O 3 and 29.5 mol% Al 2 O 3 ). Based on the current results and other published data, the pseudobinary system between Al 2 O 3 and Y 2 O 3 is revised.