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Posted on: 4/3/2009 12:00:00 AM... At first, David Seidman wasn’t sure about the prospect of an honorary symposium for his 70th birthday. “I was somewhat reluctant, but on reflection I thought it would be an excellent way to reconnect with the many people I have interacted with over the years,” said the Walter P. Murphy Professor of Materials Science and Engineering, Northwestern University. “And, this certainly was true. I felt really honored and enjoyed it both scientifically and socially.”

The symposium, “Advanced Characterization and Modeling of Phase Transformations in Metals in Honor of David N. Seidman” was a highlight for many at the TMS 2009 Annual Meeting in February. More than 50 abstracts were submitted, including contributions from Seidman’s colleagues and former students. Approximately half of these papers were invited, with 90 percent of those individuals agreeing to come, even when it meant making a long journey overseas. Said Robert Averback, symposium organizer and Donald W. Hamer Professor of Materials Science and Engineering at the University of Illinois, “With David’s achievements, he deserved something larger. When thinking how to appropriately honor the occasion of his birthday, my first thought was to try TMS.”

The idea for the symposium actually sprang from a casual conversation when Seidman’s wife, Shoshanah, mentioned to Roy Benedek that the milestone birthday was approaching. Benedek, currently Special Term Appointee (Physicist) at Argonne National Laboratory, discussed the possibility of commemorating the event with Averback, whom he had known since their postdoctoral student days with Seidman’s group in the early 70s. “Given David’s standing in the field of materials science, both Bob and I felt that a symposium in David’s honor would be appropriate and welcomed by the community,” he said. “The maturity and sophistication of the materials science field that we take for granted owe a great deal to David’s efforts.”

Early Impressions
David Seidman is considered one of the world’s leading authorities in atom-probe tomography, and is credited for designing the first atom-probe field ion microscope (FIM) with full computer control for high mass resolution, setting the standard for future instrument design. His talents and intellect were evident early on, as his thesis advisor and post doctoral supervisor, Robert W. Balluffi, Adjunct Professor in the Department of Materials Science and Engineering, Cornell University, remembers.

“He had—and has—many superior qualities,” Balluffi said. “In particular, he has an ability and willingness to take on unusually difficult and ambitious experimental work that is cleverly designed in order to obtain new and critical information at the forefront of the field of materials science.”

Georges Martin, Scientific Advisor of “Haut Commissaire à l’Énergie Atomique,” France, also vividly recalls his impression of Seidman’s earliest work. “My very first contact with David Seidman occurred reading the very first paper he published in Physical Review together with his thesis advisor, Robert Balluffi (Phys Rev 139 (1965) 1824),” he said. “By a combination of highly skilled experimental work and clever simple modeling, David proved that vacancies in metals originate at dislocations. In these days, it had been known for more than 20 years that vacancies do mediate diffusion in solid metals, but the source of vacancies was unknown. This experiment fixed the framework of many investigations to come, particularly the response of metals to irradiation induced damage production.”

Martin continued that, when he finally met Seidman in person at Cornell University in 1971, “His interest had shifted to field-ion microscopy and he was performing an extremely difficult study—the observation of the core of displacement cascades resulting from ion irradiation in tungsten. Because of the lack, in these days, of position sensitive detectors and of digital data recording systems, David had imported into physical metallurgy a technique of common use in high energy particle physics for analyzing nuclear reactions. This involved blindly recording on a movie camera the FIM image of the tip in the course of field evaporation, and then watching the movie, frame by frame, in order to pinpoint the few defects and their relative position! This gave the very few available data on the structure of displacement cascades in real metals.”

“I was fascinated by the possibility, as a Ph.D. student, of studying point defects in irradiated or quenched metals on an atomic scale,” said Seidman of his early career. “This drew me to utilizing field-ion microscopy to initially study both topics at Cornell University as an assistant professor of materials science and engineering. With the invention of the atom-probe field-ion microscope in 1968, I was strongly stimulated to use this brand-new instrument to study chemistry on an atomic scale of internal interfaces, first stacking faults and then grain boundaries. I started this research at Cornell University and then continued with this topic at Northwestern University. The primary factor compelling me to use these instruments was the desire to understand how atomic scale behavior relates to mesoscale and/or macroscopic scale phenomena in materials science.”

Pushing Boundaries
As the Founding Director of the Northwestern University Center for Atom-Probe Tomography, Seidman has more recently focused on combining simulations and experiment to understand the structure and chemistry of buried interfaces and grain boundaries. He has also employed this approach to study solid-state phase transformations in great detail, which he showcased at the Material Research Society’s prestigious David Turnbull Lecture in December 2008. Currently, Seidman is using atom-probe tomography to study phase separation of high-temperature structural alloys on an atomic scale, model nickel-based superalloys, and aluminum-scandium based alloys. Additionally, he is studying silicidation reactions with atom-probe tomography on an atomic scale, which is relevant to the problem of fabricating integrated circuits with finer and finer lines.

“With the development of three-dimensional atom-probe tomography I was further stimulated to study atomic scale phenomena and this has proven to be an extremely exciting time of my scientific career,” said Seidman. “My dream is that atom-probe tomography will be widely accepted by materials scientists as an important instrument in their study of a broad range of scientific and engineering problems. It gives me a great deal of personal satisfaction to see young Ph.D. and post-doctoral students becoming excited about this technique and to want to make further advances with it on their own.”

A Legacy of Scientists
Although his contributions to the body of materials science knowledge are numerous and well-documented, David Seidman has shaped the future even more profoundly through the minds and imaginations of his students.

Chantal K. Sudbrack, visiting research scientist at Northwestern University, is a recent Ph.D. and post doctoral student of Seidman’s. “I learned from Professor Seidman to look and question data deeply and critically,” she said. “This has had a profound influence on how I approach research problems.”

“Career-wise, Professor Seidman's guidance has been paramount in my learning how to be a successful and well-rounded scientist,” she continued. “He encouraged me to pursue various awards, mentor undergraduate student research, contribute to and review grants associated with my project, and attend additional training courses important to my research. In lieu of himself, he would recommend me for invited talks at technical conferences. I am thankful for the degree of exposure his support has afforded me. And, mentoring undergraduates has definitely helped improve my management skills.”

As one of his first students at Cornell, Arnold S. Berger, Senior Lecturer, University of Washington, Bothell, shared in some of Seidman’s earliest accomplishments. For his thesis, he looked for monvacancies and divacancies in high-purity platinum wires that were quenched from high temperature. With Baluffi as his major advisor and Seidman as his thesis advisor, he used electrical resistivity to determine the concentration and then used the field-ion microscope with Seidman to see them. “I was the first person to actually see a divacancy,” he said.

For his post-doctoral research, Berger built Seidman’s first atom-probe FIM. “Working with David I learned that I had a knack for designing and building high-speed digital electronics and computer control systems,” he said. Berger eventually left materials science to pursue a career as a computer scientist, with an emphasis on embedded systems and hardware design, but still draws on lessons that he learned as part of Seidman’s group.

“I always saw David as a colleague, not my boss,” he said. “He gave me a lot of freedom to do my research and learn by doing. I think that most shaped my perspective on working with people in general, and with my own students.”

Constant Questions
Although David Seidman has played the role of teacher and mentor for many years, he believes his own learning is far from finished. “I’ve found that it is important to keep asking questions about what one is studying and to always play the role of the devil's advocate in both performing experiments and analyzing one's experimental results,” he said. “Additionally, I learned that it is important to couple experiments with both models and simulations of one's experimental results and that the combination of both is extremely important for understanding how Nature works in detail. It is also important for experimentalists to speak with theoreticians and computational materials scientists if one is to understand deeply the results of one's experimental results.”

Averback said that it is this rigorous, uncompromising quest for knowledge that makes Seidman’s work and every article he has written “an education to the reader.”

“I admire that he’s grown constantly throughout his career,” said Averback. “He is still a person in progress, and still looking for an idea or an answer.”

Sudbrack said that Seidman’s scientific curiosity is not limited to his field of expertise. “Throughout the academic year, the Department of Materials Science and Engineering at Northwestern hosts their weekly departmental colloquium,” she said. “Independent of whether the speaker is talking about polymers or quantum dots or first principles simulations, Professor Seidman always has an interesting comment or question to bring to the discussion.

“Seriously, one would be hard-pressed to recall a colloquium where Professor Seidman DID NOT ask a question.”

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