MICROSTRUCTURAL CHARACTERIZATION OF THE DISPERSED PHASES IN AL-CE-FE SYSTEM

Analytical electron microscopy studies were conducted on a rapidly solified Al-8. 8Fe-3. 7Ce alloy and arc melted buttons of aluminum rich Al-Fe-Ce alloys to determine the characteristics of the metastable and equilibrium phases. The rapidly solidified alloy consisted of binary and ternary metastable phases in the as-extruded condition. The binary metastable phase was identified to be Al//6Fe, while the ternary metastable phases were identified to be Al//1//0Fe//2Ce and Al//2//0Fe//5Ce. The Al//2//0Fe//5Ce was a decagonal quasicrystal while the Al//1//0Fe//2Ce phase was determined to have an orthorhombic crystal structure belonging to space group Cmmm, Cmm2, or C222. Microscopy studies of RS alloy and cast buttons annealed at 700 K established the equilibrium phases to be Al//1//3Fe//4, Al//4Ce, and an Al//1//3Fe//3Ce ternary phase which was first identified in the present study. The crystal structure of the equilibrium ternary phase was determined to be orthorhombic with a Cmcm or Cmc2 space group. The details of X-ray microanalysis and convergent beam electron diffraction analysis are described.