X-RAY SINGLE CRYSTAL DIFFRACTION INVESTIGATION ON Ni1+xAl1-x. P. Paufler, J. Faber, G. Zahn, Institut fr Kristallographie und Festkrperphysik, Technische Universitt Dresden, D 01062 Dresden, Germany
Using four-circle diffractometer and Buerger precession camera with an image plate the structure of Bridgman grown single crystals of stoichiometric and nickel rich (x = 0.08) Ni1+xAl1-x (Pm-3m) has been refined. Moreover, samples were deformed plastically at 800 - 900 C.
Lattice parameters obtained from 120 reflections agree with literature values at room temperature [1-3]. In addition data between 120 and 320 K have been obtained for both lattice parameters a and thermal expansion coefficients a. These are for x = 0: a = 2.8872(2) at r.t. and a=1.4(2)10-5 K-1 between 120 and 320 K; for x = 0.08: a = 2.8798(2) .
Refinement of size occupancy factors on integrated intensity data leads to Ni on Al positions for the nickel rich sample (s.o.f. NiAl = 0.074(10)). This agrees well with results taken from electron beam microanalysis (x=0.078(23)).
Buerger precession exposures were taken from deformed crystals in order to analyze the shape of reciprocal lattice points.
[1] A. Taylor and N. J. Doyle: J. Appl. Cryst., 1972, 5, 201-209
[2] P. Georgopoulos and J. B. Cohen: Scr. Metall., 1977, 11, 147-150
[3] R. W. Clark and J. D. Wittenberger: in Thermal expansion 8 (ed. T. A. Hahn, 1984) 189-196, New York Plenum Press.