Atomic short-range order determination in gold-25 atomic percent iron and nickel-12.5 atomic percent silicon: A synchrotron x-ray diffuse scattering study

The short-range order (SRO) structure of a Gold-25 atomic percent Iron single crystal was studied using wide-angle diffuse synchrotron x-radiation scattering at room temperature. Two heat-treatments were investigated; a 400$\sp\circ$C aging treatment for two days and a second at 440$\sp\circ$C for five days, both preceded by solution treatment in the single-phase field and water-quenched to room temperature. Evolution of the SRO structure with aging was determined by fitting the two sets of Cowley-Warren SRO parameters to a pair of 140,608-atom models. The microstructures, while quite disordered, showed a trend with aging for an increasing volume fraction of an Fe-enriched and an Fe-depleted environment. The Fe-enriched environment displayed a slight preference for Fe segregation to the $\{$110$\}$ and $\{$100$\}$ fcc matrix planes. A major portion of the Fe-depleted environment was found to contain elements (and variations of these elements) of the D1$\sb{\rm a}$ ordered superstructure. The SRO contained in the Fe-depleted environment may be best described in terms of the standing concentration wave packet (SCWP) model. This study provides, for the first time, a quantitative real-space view of the atomic arrangements which make up both environments in the SRO structure of Au-25at.%Fe.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Materials Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2011

Author dc:creator

• Anderson, Jeffrey P.

Contributors dc:contributor

• Chen, Haydn

• Engineering, Metallurgy
• Engineering, Materials Science

Statement dc:rights

• Copyright 1992 Anderson, Jeffrey P.

Language dc:language

eng

Identifier

AAI9215768
(UMI)AAI9215768

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/21774