Orthorhombic ε-phases and transitional structures in Al-Pd-(Fe)

The results of an investigation of the structures formed in the range of about Al73Pd27 to Al76Pd14Fe10 by electron diffraction and high-resolution transmission microscopy are reported. The orthorhombic epsilon(6), epsilon(16), epsilon(22) and epsilon(28) phases were observed in specific compositional sub-ranges. Their lattice parameters aapproximate to2.34 and bapproximate to1.62 nm are essentially the same while the c parameters are approximate to1.23, 3.24, 4.49 and 5.70 nm, respectively. Apart from these regular structures, also structures aperiodic along the c-direction are revealed at intermediate compositions. Thus, inside the wide epsilon-phase range only slight continuous variations of the orthorhombic a and b cell parameters are accompanied by complicated modulations of the c cell parameter.