Materials Science Forum, Vol.519-521, 395-400, 2006
Microstructure and phase composition of Al-Ce-Cu alloys in the Al-rich corner
Al-Cu-Ce alloys have been studied in the Al-rich corner using the microstructural (LM and SEM), thermal (direct and DSC), X-ray diffraction and electron probe microanalysis techniques. Three cross-sections were of particular interest: (a) at 20%Cu (up to 12.5%Ce), (b) at 14%Cu (up to 10%Cu) and (c) at a ratio Cu:Ce=2:1 (up to 10%Ce and 20%Cu). As-cast alloys and those after annealing at 540 and 590 degrees C were studied. Boundaries of appearance of the Al8CeCu4 primary crystals and ternary eutectic involving the phase Al2CU were determined. The radial cross section (Cu:Ce=2:1) is supposed to be of quasibinary type as ternary eutectic does not form. The temperature and concentrations of the eutectic reaction L-(Al)+CeCu4Al8 were found to be 610 degrees C, 14%Cu and 7%Ce. This binary eutectic has fine microstructure and is capable to fragmentation and spheroidization during heating. The paper considers possibility of using the Al-Cu-Ce system for developing novel Al casting alloys with significantly improved casting properties (hot tearing and fluidity) in comparison with 2xx commercial alloys.