Metallurgy Division Publications - NISTIR 7017

Executive Summary

This Annual Report describes the major technical activities, accomplishments, and areas of scientific expertise in the Metallurgy Division of NIST Materials Science and Engineering Laboratory for FY2003 (October 2002 through September 2003). Through this report, we provide some insight into how our research programs meet the needs of our customers, how the capabilities of the Metallurgy Division are being used to solve problems important to the national economy and the materials metrology infrastructure, and how we interact with our customers to establish new priorities and programs. Contact information for our staff is provided if you would like to participate in any of these projects or if have any questions. We also welcome feedback and suggestions on how we can better serve the needs of our customers and encourage increasing collaboration to this end.

Mission of the NIST Metallurgy Division

Our mission is to provide critical leadership in the development of measurement methods, standards, and fundamental understanding of materials behavior needed by U.S. materials users and producers to become or remain competitive in the changing global marketplace.

As a fundamental part of this mission, we are responsible not only for developing new measurement methods with broad applicability across materials classes and industries but also for working with individual industry groups to develop and integrate measurements, standards, software tools, and evaluated data for specific, technologically important applications.

Establishing Priorities

We examine a wide range of research opportunities and make choices for our research portfolio based on: the match to the NIST mission, the magnitude and immediacy of industrial need, whether the NIST contribution is critical for success, the anticipated impact relative to our investment, our ability to respond in a timely fashion with high-quality output, and the opportunity to advance mission science. This requires us to establish our research priorities through extensive consultation and collaboration with our customers in U.S. industry and with our counterparts in the international metrology community using a variety of methods including industrial roadmapping activities, workshops, technical meetings, standards committee participation, and individual consultation with our customers. For us to have the highest possible impact also requires that we work to be at the forefront of materials science.

Within the context of industrial relevance and potential impact of our research, technology trends strongly influence the technical directions addressed by NIST. We prefer to work in rapidly evolving technologies, where advances in measurement science are needed to understand the limitations on system behavior and, therefore, where our contributions are likely to have an impact on the course of technology. For NIST as a whole and the Metallurgy Division in particular, we are committed to having an impact on the measurement and standards infrastructure for nanotechnology, health care, and homeland security. Nanotechnology is not an industry sector itself but will have an impact on present and future industrial enterprises. Three new Division projects began in nanotechnology and healthcare in 2003; an additional project on Informatics and Visualization in Data Delivery was started in 2003 to examine how to best transfer our results to traditional and possible NIST customers. In 2004, we will begin two new nanotechnology projects selected through a NIST-wide competition. In collaboration with three other NIST laboratories (EEEL, ITL, PL), a major project will be started on Nanoscale Engineered Sensors for Ultra-low Magnetic Field Metrology. Low noise, ultra-low magnetic field sensors could have a significant impact on healthcare diagnostics, homeland security sensors, and magnetic data storage. In collaboration with three other NIST laboratories (CSTL, PL, and ITL), we will begin developing systems for three-dimensional chemical imaging at the nanoscale in the transmission electron microscope. This should add greatly to our understanding of the relationship between materials composition, processing, and properties, the raison d’etre of materials science and engineering. These were the only two fully funded projects in the NIST competition.

Research Portfolio

Our 2003 research portfolio focuses on fulfilling specific measurement needs of the industrial sectors: the magnetic data storage, microelectronics/optoelectronics, automotive, aerospace, and defense industries, and on developing the materials data need for the World Trade Center failure investigation. Our output consists of a variety of forms, from a fundamental understanding of materials behavior to measurement techniques conveyed through the scientific literature and oral presentations, standard reference materials, evaluated data and online databases, software tools, and sensors for on-line process control. Examples of our 2003 outputs in a few of these areas are:

• Magnetic Data Storage: In 2003, we shifted our emphasis from Giant Magnetoresistance (GMR) in Thin Films to understanding artifacts in Ballistic Magnetoresistance (BMR). In the past year, advances in the Ballistic Magnetoresistance (BMR) effect appeared to provide an enormous increase in the sensitivity of nanoscale devices. The scientific press reported the creation of devices with resistance changes as much as 10⁶ as one of the major discoveries of the year. Experiments at NIST in 2003 have found that several simple artifacts account for the results. NIST is taking a leading role in designing artifact-free metrology to provide reliable data to the magnetic sensor industry and the academic community.

• Microelectronics Packaging: In the MSEL Program on Materials for Microelectronics, we continue to provide tools for producing improved metal interconnects, from copper on-chip interconnects at the nanometer scale to lead-free solder joints on printed wiring boards. Our project on measurements and modeling of electrodeposited copper for nanometer scale chip interconnection technology continues to produce significant value to the microelectronics community. Since the beginning of the project in April 1999, we have developed a measurement technique, a theory for control of interface dynamics, and modeling software for predicting quantitatively the ability of complex electrolytes to fill vias and trenches, and we extended the NIST model to electrodeposited metals other than copper. In 2003, we used our theory as a basis for developing processing methods to increase the aspect ratios of fine features (< 50 nm) that can be filled and have transferred all of these to the appropriate industrial customers. In addition, in response to the need for improved seed layer systems articulated to us by International Sematech, we demonstrated the utility of thin ruthenium layers as combination barrier layer/seed layer in superconformal growth on patterned substrates. In the area of electronics assembly, our role in the NEMI Lead-Free Solder Task Force has wound down. With the completion of Task Force research plan in 2002, and final analysis of the results in 2003, U.S. microelectronics companies now have enough critically evaluated data to decide on whether to implement lead-free solders in manufacturing. The one open question is how important tin whiskers forming on plated component surface finishes will be for system reliability. There is a long, documented history of tin whiskers causing catastrophic short circuits in critical systems such as satellites and medical devices. In the past, Pb-Sn alloys were plated instead of Sn since Pb additions appeared to suppress whisker growth. With the requirement of Pb-free manufacturing in some regions, such as the European union, Pb additions are no longer acceptable. NIST has taken a major role in helping NEMI develop test methods for whisker growth and a fundamental understanding of the mechanisms leading to whisker formation.

• Automotive: Within the sub-program on the Forming of Lightweight Materials, we are developing standard test methods for sheet metal forming, measurements of surface roughness, and physically based constitutive laws — and measurement tools needed to reveal them. In FY2003, an x-ray stress measuring system was installed on the sheet metal formability station. With this addition, the formability facility will be capable of direct, in situ measurement of the stress in a given direction while the sample is under biaxial load. Such measurements will lead to a standard test for measuring multiaxial flow surfaces in sheet metal during stamping operations. All of our projects in the Forming of Lightweight Materials Program are performed in close collaboration with the automotive industry through formal partnerships, such as USCAR and the Freedom Car, and are formulated to help accelerate the design of forming operations for lightweight materials such as aluminum, that will ultimately improve fuel economy.

• Infrastructure Materials: NIST has developed a unique testing facility for measuring high-strain rate mechanical properties of materials at high heating rates. Based on the Kolsky bar design (also known as a split-Hopkinson pressure bar), materials can be strained at rates as high as 10⁵ s^–1 while being heated up to 1300 K at heating rates up to 5x10⁴ K/s. This facility was initially developed to provide insight and data for high speed machining of commercial alloys. In addition to this application, the Kolsky bar facility is providing the rate dependence of plastic deformation for the many types of structural steel in the World Trade Center buildings and for projectiles such as those used as military tank penetrators. We expect the facility to be useful in the future for development of data and modeling in the areas of dynamic fracture and crack arrest of high strength pipeline steels, bullets and body armor for the Office of Law Enforcement Standards, and additional issues in manufacturing.

Division Structure and Expertise

The Division is composed of 39 scientists, supported by 6 technicians, 6 administrative staff members, and more than 80 guest scientists, and it’s organized into five groups that represent the Division’s core expertise in Metallurgical Processing, Electrochemical Processing, Magnetic Materials, Materials Structure and Characterization, and Materials Performance. However, by virtue of the interdisciplinary nature of materials problems in the industrial and metrology sectors that we serve, Program teams are assembled across group, division and laboratory boundaries and, in most cases, with academic and industrial partners, to best meet our project goals. We are committed to assembling the expertise and resources to fulfill our technical goals with the speed and quality necessary to have the desired impact. We welcome your participation with us in this enterprise.

Carol A. Handwerker, Division Chief

Frank W. Gayle, Deputy Division Chief