Intermetallic Alloy Development: A Program Evaluation (1997)

Intermetallic compounds are a unique class of materials consisting of ordered alloy phases formed between two or more metallic elements where the different atomic species occupy specific sites in the crystal lattice. Intermetallic alloys with high aluminum content have been considered for use in demanding structural applications because of their inherent oxidation resistance and strength retention at high temperatures. However, they can be extremely brittle at ambient temperatures, are difficult to process, and are prone to environmental degradation.

The development program described in this report was undertaken by the Oak Ridge National Laboratory (ORNL) to increase the understanding and improve the properties of intermetallic compounds so that they could be processed and utilized as structural materials in a number of demanding high temperature environments in a number of industries. This program, which was begun in 1981, is one of the longest continuously funded materials development programs ever undertaken at ORNL. The U.S. Department of Energy Office of Industrial Technology (OIT), through the Energy Conversion and Utilization (ECUT) and Advanced Industrial Materials (AIM) programs, has provided roughly one-third of the funding to ORNL for the development and commercialization of intermetallic alloys.

In 1995, OIT's program management strategy was revised to reflect a new commitment to increasing and documenting the commercial impact of OIT programs (provided the products still met OIT goals of improving energy efficiency and reducing adverse environmental impact). OIT's research and development management strategy was changed from a “technology push” strategy to a "market pull" strategy. Seven industries—steel, forest products, glass, metal casting,

aluminum, chemicals, and petroleum refining—were found to consume more than 80 percent of the energy consumed by the manufacturing sector of the economy and to produce more than 90 percent of the hazardous waste products generated in this same sector. These seven industries, designated Industries of the Future (IOF), became the focus of OIT programs. OIT research projects are now selected and prioritized to meet the business and technological needs of the IOF.

The National Research Council Intermetallic Alloy Development Panel was established to review the progress and accomplishments of the intermetallic alloy research and development program; to describe program management strategies, including selection criteria, commercialization plans, and industry involvement; to describe successful and unsuccessful efforts to develop commercial applications for intermetallic alloys; to suggest potential applications in the OIT target industries; and to recommend criteria for selecting and prioritizing future projects for the research and development of intermetallic materials and processes.

This study is part of the National Research Council Committee on Industrial Technology Assessments (CITA), which was established to evaluate the OIT program strategy, to provide guidance during the transition to the new IOF strategy, and to assess the effects of the change in program strategy on crosscutting technology programs, that is, programs to develop technology applicable to several industries.

Intermetallic alloy development was selected as the first panel topic under CITA because the intermetallic alloy program is a mature program already focused on crosscutting research and development. The emphasis of this report is on lessons that can be derived from the development of Ni₃Al alloys and processes, which have been the focus of the OIT intermetallics research program at ORNL. These lessons may be of benefit to OIT in the implementation of the IOF strategy throughout the OIT program.

The panel's findings include a review and assessment of the intermetallic alloy development program and recommendations for the future focus of the program as well as an assessment of the implications for the entire OIT program and the transition to the IOF strategy. The major recommendations are included in this summary. Additional recommendations can be found in Chapter 4 of the report.

Overall, the ORNL intermetallic alloy development program has been successful in terms of the technical goals and objectives established by the program, i.e., to develop high strength, ductile intermetallic alloys that can be processed and utilized for high-temperature structural applications. The program has been well managed, with effective integration of program elements—from basic research through production-scale demonstrations—and effective coordination of program goals and responsibilities among participating funding and research organizations.

In the panel's judgment, the ORNL intermetallics program has been a successful science and technology development program for a number of reasons. These include consistent and continuous funding (since 1982); effective integration of basic and applied research and development by universities, other national laboratories, and industry; the flexibility to reorient and refocus research efforts in response to promising results or identified needs; and the establishment of partnerships and collaborations with industry to identify industry needs and establish practical goals for technology development.

The ORNL intermetallic alloy development program has made significant technical advances since its inception—from basic exploratory research and characterization through process development and scaling. The early decision to focus on Ni₃Al alloys and to concentrate on optimizing alloy composition, characterizing material behavior, and developing production-scale processing methods has been critical to the success of the program.

Technical accomplishments in the characterization and development of Ni₃Al alloy compositions include:

• the identification of brittle grain-boundary fracture mechanisms at ambient temperatures and the substantial loss of ductility at intermediate temperatures as major material deficits

• the determination of causes for brittle ambient-temperature fracture (moisture-induced embrittlement) and intermediate-temperature ductility loss (dynamic oxygen-induced degradation)

• the improvement of ductility by microalloying with boron and chromium

• the improvement of elevated temperature strength and processibility using standard alloying techniques, including solid-solution strengthening, dispersion strengthening, and improving strength, weldability, and castability

In the panel's judgment, some of the most significant accomplishments of the intermetallic alloy research program have been in the development of manufacturing processes. Developments in this area include:

• a production-volume melting process that maintains aluminum concentration while melting higher-temperature-melting constituents (Exo-melt® process)

• methods and alloy modifications for low-cost casting processes

• materials (e.g., weld wire) and processes for making structural welds and weld repairs

The results of successful use of Ni₃Al alloys in a variety of trial production applications, as well as recent commercial orders for furnace transfer rolls in steel mills and heat-treat furnace fixtures, indicate that the commercial application of these alloys is likely to expand in the next several years. However, although Ni₃Al alloys have performed well in production-scale trials, it is unclear at this time if the level of successful commercial application will repay the research investment. Criteria that need to be considered in the full commercialization of a new material include:

• The availability of alternative materials. To replace an established material, factors other than performance must be considered. These include the cost and supply of raw materials; production capability; cost of materials, fabrication processes, tooling, and facilities; demonstrated reliability; and supplier infrastructure.

• Industrial participation. Successful commercialization requires a strong, committed, and, in some instances, lucky industrial proponent who understands the real hurdles and motivation for industrial acceptance.

• Technology Readiness. The technology, especially the processing technology, must be substantially developed prior to commercialization.

These criteria have been a part of the commercialization strategy for the ORNL intermetallics program, but ultimately ORNL depends on industry to commercialize new technologies.

Throughout the ORNL intermetallic alloy development program, interaction with industrial participants has been critical to identifying needs and priorities. Interactions with industry have helped ORNL focus on optimizing alloy compositions and developing process technologies to meet industrial needs. In addition to the collaboration mechanisms previously used by ORNL (cooperative research and development agreements, cofunded research projects, license agreements), IOF industry "vision documents" and road maps would also be helpful for identifying industry needs and priorities that can be met through the application of intermetallic alloys. Examples of potential applications include expanding the use of Ni₃Al for hot metalworking (dies, fixtures, furnace components), developing nickel and iron aluminides for processing equipment used in high temperature and corrosive environments in the chemical and refining industries, and using Ni₃Al in transfer and processing rolls for the steel and paper industries.

In addition to characterizing the physical and mechanical properties of Ni₃Al, which has been emphasized in previous work, the focus should now shift to

modeling solidification (casting and welding) processes and to establishing production processing standards and methods for machining and welding nickel and iron aluminides. This shift would extend the industrial applications and improve the potential for commercialization of intermetallic alloys.

The panel believes that reliance on industry needs alone, even with an effective identification strategy, has inherent drawbacks. For example, important crosscutting or exploratory research programs might not be supported if they are not identified as high-priority industry needs by any one group.

Recommendation. ORNL should focus research on optimizing alloys and developing process technologies for a select number of alloy families for which ORNL has unique expertise and capability. In addition to the Ni₃Al-based alloys emphasized in previous programs, ORNL has particular experience with iron aluminides (Fe₃Al, FeAl).

Recommendation. ORNL should continue to emphasize the development of manufacturing process technology for selected alloys to maximize opportunities for commercialization and technology transfer to industry.

Recommendation. ORNL should emphasize low-cost processes in the development and optimization of intermetallic alloys.

Recommendation. OIT and the ORNL intermetallic alloy development program should use the following approach to identify and prioritize research programs:

• Identify IOF needs and priorities that can be met through the application of intermetallic alloys.

• Establish, with input from IOF teams interested in the commercial uses of intermetallic alloys, a target level of support for crosscutting research and development programs.

• Identify projects with the potential to meet identified industry needs and develop material and process technology goals based on these potential applications.

• Emphasize crosscutting projects that could lead to commercial application in more than one industrial sector.

The lessons learned from the development of Ni₃Al alloys and processes can provide OIT with general guidelines for coordinating and managing several funding and research organizations and for establishing effective industrial

collaborations. These guidelines can be used in the implementation of the IOF strategy throughout the OIT program.

Even though the ORNL intermetallic alloy development program has relied on industrial participants to establish needs and priorities, the "profit-based" metrics used in industry for measuring the efficacy of research and development may not be appropriate for government-funded long-term research. IOF guidance is useful for ensuring that the program is relevant, but the panel suggests that short-term (i.e., one to three years) commercial potential should not be the primary "compass" directing the selection of OIT projects. In the panel's judgment, metrics compatible with Department of Energy and OIT organizational objectives for comparing and selecting programs for the IOF program should include the potential for conserving energy, the potential for reducing waste, consistency with IOF business objectives and technology road maps, commercial potential/market value, and potential use in more than one industrial sector (crosscutting technologies).

Because OIT is part of the federal research and development establishment, it cannot participate fully and actively in the commercialization process, especially in the later stages when the product is brought to market. Rather, the technologies developed by OIT must be commercialized by industry.

Recommendation. OIT should emphasize the early involvement of key industrial participants, including the suppliers, producers, and users of particular materials or process technologies. OIT should adopt collaboration mechanisms, such as cooperative research and development agreements, cofunded research programs, exchanges of personnel, and the use of laboratory user centers (e.g., the ORNL Metals Processing User Center).

Recommendation. OIT should support joint projects with potential suppliers and users of a specific technology to demonstrate and debut the technology.

Recommendation. When licensing technology developed by an OIT research and development program, OIT should specify the relationship between the research and development program and the licensee's business strategy. OIT should not enter into exclusive licensing arrangements that rely on unrealistic technology development for commercialization (i.e., licensing too early) or that unnecessarily restrict or preclude use of the technology by other industries.

Recommendation. OIT should develop a mechanism for the orderly termination of (1) projects that have met OIT objectives and have progressed to the final stage of commercialization (market introduction) and (2) projects that do not have sufficient industrial interest to support demonstration, process development, and scale-up.