CE-CU-SN SYSTEM - EXPERIMENTAL-DETERMINATION OF THE LIQUIDUS SURFACE IN THE CE-RICH CORNER

The phase diagrams of the binary Ce-Cu and Ce-Sn systems as well as th e ternary Ce-Cu-Sn system were studied in the Ce-rich part. The alloys were prepared by melting in an induction furnace under argon and then annealed at 350 degrees C for two weeks. The DSC results have been co mbined with microstructural observations carried out by SEM/EDS to det ermine the liquidus surface. The following fields of primary crystalli zation have been observed: delta Ce, gamma Ce, Ce3Sn, Ce5Sn3, et tau(1 ) (Ce5CuSn3). A number of invariant reactions have been detected by DS C. A ternary eutectic point has been identified at 420 degrees C, clos e to the binary eutectic Ce-Cu at 424 degrees C. Several invariant rea ctions have been observed at 780, 775, 770 and 530 degrees C but remai n to be defined. Two U-type (transition peritectic) ternary reactions have been identified (U-2 at 699 degrees C and U-3 at 510 degrees C).