The UCoAl ternary system: Phases formation and isothermal section of the phase diagram at 900 °C

Phase relations in the Uranium-Cobalt-Aluminum ternary system have been investigated by X-ray diffraction and scanning electron microscopy. A total number of six ternary phases were found to form in the isothermal section at 900 °C among which three have been discovered in the present study namely; U2Co6Al19 (Monoclinic, C2/m, a=17.4617(3)Å, b=12.0474(2)Å, c=8.2003(1)Å, β=103.915(1)), U2Co3Al9 (Orthorhombic, Cmcm, a=12.789(1), b=7.477(1), c=9.258(1)), U3Co4+xAl12−x (Hexagonal, P63/mmc, a=8.6518(2)Å, c=9.2620(2)Å). Another new ternary compound: UCoAl4 (Hexagonal, P-62m, a=9.161(1)Å, c=4.114(1)Å was found to form only in as-cast samples.