SOLIDIFICATION BEHAVIOR OF THE AL2CU PHASE

The Al-Cu phase diagram was redetermined in the concentration range be tween 31 and 37.5 at.% Cu applying differential thermal analysis, magn etothermal analysis and optical microscopy. The solubility of the Al2C u phase which is formed in a peritectic reaction at 592 degrees C rang es at 549 degrees C from 32.05 to 32.6 at.% Cu and at 250 degrees C fr om 32.4 to 32.8 at.% Cu. The alloy melts investigated exhibit a strong tendency for undercooling. A metastable Al2Cum phase with the composi tion of 32.75 at.% Cu and an Al2Cu crystal structure solidifies direct ly from the melt applying cooling rates between 1 to 20 K/min. The res pective undercooled states and metastable phase equilibria are provide d.