Dresden 2009 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 33: Phase Transitions I
MM 33.4: Talk
Wednesday, March 25, 2009, 15:30–15:45, IFW B
Near-surface microstructure of Ni-rich Ni-Pt — •Markus Engelke1, Bernd Schönfeld1, and Philip Willmott2 — 1LMPT, Department of Materials, ETH Zurich — 2SLS, Paul Scherrer Institut, Villigen
While the surface structure and the local atomic arrangement in the bulk of Ni-Pt alloys have been repeatedly studied, not much is known about the intermediate regime accessible by grazing incidence diffraction. Here, Ni-23.2 at.% Pt (110) was investigated at 923 K under UHV using synchrotron radiation at an angle of incidence of 0.75 times the critical angle of total reflection. Diffuse scattering shows maxima of about 5 Laue units at 100 positions. From the diffuse scattering registered at positions in-plane and out-of-plane, Warren-Cowley short-range order parameters were recovered. The assumption of a cubic as well as a tetragonal structure for data evaluation results in similar features; dominant values for nearest and next-nearest neighbors and signs of the parameters as expected for L12 type of local order.