Ordering Mechanism in Ni-Cr Alloys: Theory and Experiment

Autor: Don M. Nicholson, R.H. Howell, F. J. Pinski, Duane D. Johnson, G. M. Stocks, M. J. Fluss, W. Schweika, Patrice E. A. Turchi, A.L. Wachs
Rok vydání: 1989
Předmět:
Zdroj: MRS Proceedings. 166
ISSN: 1946-4274
0272-9172
Popis: Recently, short range order (SRO) parameters have been extracted from the neutron diffuse scattering intensities on Ni-Cr alloys with 11 to 25 at. pct. chromium. These data were analyzed using inverse-Monte Carlo simulations to extract atomic interactions and the results suggested the existence of a well defined, flat sheet of Fermi surface normal to the [110] direction. In this paper, this suggestion is investigated with a series of calculations which are based on the first-principles Korringa-Kohn-Rostoker-coherent-potential-approximation (KKRCPA). We calculate the electronic structure and the Bloch spectral function at the Fermi energy. We then proceed to calculate the effective cluster interactions using the generalized perturbation method (GPM) and compare them with the above-mentioned experimentally deduced interactions. In addition, we present preliminary results of two-dimensional angular correlation of positron annihilation radiation (2D-ACPAR) measurements, which probe the fermiology of this alloy system. The positron experiments demonstrate the existence of well-defined features in the Fermi surface of Ni89Cr11 but our calculations still have not yet established the origin of SRO in this system.
Databáze: OpenAIRE
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