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Title: The role of ALCHEMI in understanding the properties of ordered intermetallic alloys

Abstract

After one and one-half decades of development, ALCHEMI is approaching the status of an established analytical technique. Many of the problems that have plagued ALCHEMI, especially for the analysis of ordered intermetallic alloys, are now well understood, and accurate site-distributions can be extracted from a variety of intermetallic alloys. This paper begins with an overview of the factors that can lead to large systematic errors or gross misinterpretations of ALCHEMI data, with illustrations from a variety of ordered intermetallic alloys. The paper concludes with a discussion of ALCHEMI in the broader context of understanding the properties of ordered intermetallic alloys. The results of systematic studies are used to illustrate the role of ALCHEMI in determining the competing effects of thermodynamic and kinetic factors during alloy processing and the correlation of alloy properties with the atomic site distributions on which the properties ultimately depend.

Authors:
Publication Date:
Research Org.:
Oak Ridge National Lab., Metals and Ceramics Div., TN (United States)
Sponsoring Org.:
USDOE Office of Energy Research, Washington, DC (United States)
OSTI Identifier:
290936
Report Number(s):
ORNL/CP-98595
ON: DE99000361; BR: KC0201010; TRN: AHC29901%%141
DOE Contract Number:
AC05-96OR22464
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: [1998]
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CRYSTAL STRUCTURE; INTERMETALLIC COMPOUNDS; MICROANALYSIS; RELIABILITY; CORRELATIONS; EXPERIMENTAL DATA

Citation Formats

Anderson, I.M.. The role of ALCHEMI in understanding the properties of ordered intermetallic alloys. United States: N. p., 1998. Web. doi:10.2172/290936.
Anderson, I.M.. The role of ALCHEMI in understanding the properties of ordered intermetallic alloys. United States. doi:10.2172/290936.
Anderson, I.M.. Sun . "The role of ALCHEMI in understanding the properties of ordered intermetallic alloys". United States. doi:10.2172/290936. https://www.osti.gov/servlets/purl/290936.
@article{osti_290936,
title = {The role of ALCHEMI in understanding the properties of ordered intermetallic alloys},
author = {Anderson, I.M.},
abstractNote = {After one and one-half decades of development, ALCHEMI is approaching the status of an established analytical technique. Many of the problems that have plagued ALCHEMI, especially for the analysis of ordered intermetallic alloys, are now well understood, and accurate site-distributions can be extracted from a variety of intermetallic alloys. This paper begins with an overview of the factors that can lead to large systematic errors or gross misinterpretations of ALCHEMI data, with illustrations from a variety of ordered intermetallic alloys. The paper concludes with a discussion of ALCHEMI in the broader context of understanding the properties of ordered intermetallic alloys. The results of systematic studies are used to illustrate the role of ALCHEMI in determining the competing effects of thermodynamic and kinetic factors during alloy processing and the correlation of alloy properties with the atomic site distributions on which the properties ultimately depend.},
doi = {10.2172/290936},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sun Nov 01 00:00:00 EST 1998},
month = {Sun Nov 01 00:00:00 EST 1998}
}

Technical Report:

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  • A detailed understanding of the structure of ordered intermetallic systems is difficult at best, causing a serious disconnect in the typical process-structure-properties approach to alloy development. Basic information, like the site substitution schemes of various alloying elements, partitioning behavior in multiphase alloys, and the dependence of these phenomena with concentration and higher order alloying additions is necessary to predict and understand the effect of various alloying schemes on the physical and mechanical properties of a material. It is only recently that theoretical methods can begin to provide useful insight in these areas, as most current techniques suffer from strong limitationsmore » including the type and number of elements that can be considered and the crystallographic structure of the resulting phases. The Bozzolo-Ferrante-Smith (BFS) method for alloys was designed to overcome these limitations, with the intent of providing a useful tool for the theoretical prediction of fundamental properties and the structure of multi-component systems. The role or potential contributions of theoretical procedures like the BFS method to the alloy design process are discussed with a specific emphasis on work that has been conducted on NiAl-based alloys. After a brief description of the method and its range of applications, the authors will concentrate on the usefulness of BFS as an alloy design tool. The theoretical determination of site substitution schemes for individual as well as collective alloying additions to NiAl, the resulting behavior with respect to solubility limits and second phase formation, and the concentration dependence of the lattice parameter will be demonstrated.« less
  • ALCHEMI determinations of sublattice occupancy in Cu{sub 50}Au{sub 50-x}Pd{sub x} alloys and Ni{sub 3}Al-based alloys containing Fe, Co, and Hf illustrate some practical limitations of the technique. The restrictions imposed by domain size, disordered surface layers, illumination conditions, coherent bremsstrahlung peaks, ionization delocalization effects, and the need for axial rather than planar channeling are discussed. 12 refs., 3 figs.
  • The travelers spent one week each at ORNL and LANL visiting the groups which are currently involved in the Materials by Design directive of the ECUT Materials Program. The progress made and problems encountered in using the senior traveler's phenomenological structure maps in the search for new cubic, ductile, ordered intermetallics were reviewed. The problems of limited solid solubility and brittleness of certain cubic alloys were noted and a specific trialuminide system identified for future collaborative experimental and theoretical investigation.
  • The traveler was invited to tour through and provide technical guidance for the Japan National Project on High-Temperature Ordered Intermetallic Alloys, which was sponsored by MITI, Japan. The traveler stayed in Japan for three weeks and visited a total of nine research institutes and industrial laboratories active in intermetallic research. During the visit, the traveler learned of the recent research and development of two intermetallic model materials--titanium aluminide (TiAl) and niobium aluminide (Nb{sub 3}Al) selected by MITI. The traveler also gave lectures on recent advances in ordered intermetallic alloys with emphases on brittle fracture and ductility improvement. The MITI's projectmore » has provided leadership and stimulated interest in intermetallic research and development among Japan industries.« less
  • The traveler gave a week-long lecture on Ordered Intermetallic Alloys --- Physical Metallurgy, Mechanical Behavior and Alloy Design at the Instituto de Pesquisas Energeticas e Nucleares, National Commission for Nuclear Energy, Brazil. While in Brazil, the traveler learned about recent research on Ni{sub 3}Al alloys and industrial interest in ordered intermetallics.