Memorial Tributes: Volume 27
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  • U. FRED KOCKS (1929-2023)
    U. FRED KOCKSU. FRED KOCKS

     

    BY EDUARD ARZT

    ULRICH FRITZ HEINRICH KOCKS, a pioneer in the field of physical metallurgy, passed away on May 6, 2023, at age 93.

    Born in Germany on Nov. 25, 1929, he studied physics at the University of Goettingen under the theoretical physicist Richard Becker, a student of Max Planck (NAS 1926). Fred immigrated to the United States with his wife Marianne (née Roettger) in 1955, where friends persuaded him to change his first name to the more easily pronounced “Fred.” In 1959 he obtained a Ph.D. in applied physics from Harvard University under the guidance of the eminent metallurgy professor Bruce Chalmers (NAS 1975). He spent another six years there as a faculty member in the Division of Engineering and Applied Physics and became a U.S. citizen in 1962, formalizing his name as Ulrich Fred Kocks (usually abbreviated as U.F. Kocks). Subsequently he spent his scientific life at two national laboratories: In 1965 the Argonne National Laboratory invited him to establish a group on mechanical properties, and in 1983 he became a founding member of the Center for Materials Science at the Los Alamos National Laboratory. His research career spanned five decades and was characterized by pioneering work in physical metallurgy, multiple books and articles, and numerous awards.

    From his early work on slip in copper crystals during his Ph.D. studies, Fred pursued an interest in the deformation of crystalline materials throughout his distinguished career. The dominant theme of his opus is the description of the polycrystalline nature of metals (their “texture”) and its connection to plastic deformation as well as the progressively increasing obstruction as deformation proceeds (“work hardening”). These fundamental mechanisms are at the heart of the strength and the processing schemes of metals and, hence, of their success in demanding applications such as transport, construction, and aerospace.

    His first landmark publication in this field was “A statistical theory of flow stress and work hardening,”1 published in Philosophical Magazine in 1966 as a result of his sabbatical at the Technical University of Munich, Germany. It was followed by the 1970 paper in Metallurgical Transactions, “Relation between polycrystal deformation and single-crystal deformation.”The effects of finite sample volume on crystallographic slip and dislocation interactions, which are of high relevance in today’s microelectronic materials, were also of interest to him during that time.

    At Argonne, a focus of his experimental work was solid-solution alloys: As foreign atoms interact with crystal defects, more complex slip mechanisms are introduced (“dynamic strain aging”). A seminal monograph was published in 1975 in the Progress in Materials Science volume series with Ali Argon (Massachusetts Institute of Technology; NAE 1989) and Michael F. Ashby (then at Harvard University; NAE 1990) titled The Thermodynamics and Kinetics of Slip.3 This extensive monograph is still consulted today by specialists in the field. In 1977, Fred chaired the Gordon Conference on Physical Metallurgy. Subsequently, he turned his interest to high-temperature deformation and creep of metals. A theory on the kinetics of flow and strain hardening, which was described in an article4 published in Acta Metallurgica in 1981, marked the beginning of a long-term cooperation with Heinz Mecking (Technische Hochschule (RWTH) Aachen, later president of Technical University of Hamburg-Harburg). Other leading colleagues with whom Fred established lasting connections included John Jonas from McGill University and David Embury (NAE 2002) from McMaster University, and later Gilles Canova from Metz (France) and Anthony Rollett from Carnegie Mellon University.

    At Los Alamos, the collaboration with many internal and external scientists formed the core of his activities. He continued his work on the kinetics of slip and work hardening with Paul Follansbee and others, which led to a landmark paper, “A constitutive description of the deformation of copper based on the use of the mechanical threshold stress as an internal state variable,”5 published in Acta Metallurgica in 1988. This paper was the genesis of the widely used Mechanical Threshold Stress model of temperature and strain-rate dependent work hardening, often referred to as the “Kocks-Mecking model.” Preferred crystallographic orientations (textures) of annealed or worked polycrystals were among his focal areas. Around this time, rocks and minerals, which exhibit crystal structures of lower symmetry than most metals, became a subject of increased interest to the materials community. Fred and Hans-Rudolf Wenk (University of California, Berkeley, Earth & Planetary Science) devoted themselves to an integrated view of metals and rocks and adapted polycrystal plasticity models to low-symmetry minerals. In 1987, Fred organized the 8th International Conference of Textures of Materials in Santa Fe, New Mexico, which was the first in the series held in the Americas and attracted a large audience; it focused on modeling of texture development, quantitative texture measurements, and experiments on complex polyphase materials. Based on a better understanding of texture effects and orientation distributions, texture research now became a quantitative discipline, both in terms of pole figure analysis and plasticity simulation. Two software programs were developed and freely distributed by the Los Alamos National Laboratory: popLA, for texture analysis and representation, and LApp, for the simulation of polycrystal plasticity. In 1998, with co-authors Carlos Tomé, Rudy Wenk, and others, Fred published a book on Texture and Anisotropy: Preferred Orientations in Polycrystals and their Effect on Materials Properties (Cambridge University Press, 1998; with a second edition in 2000). Fred and Mecking summarized their long-term collaboration in “Physics and phenomenology of strain hardening,”6 published in Progress in Materials Science in 2003.

    Fred was an internationally highly renowned researcher in the discipline of physical metallurgy. In 1999 he was elected to the National Academy of Engineering “for advancements in the theory of strength, kinetics of plasticity of metals, and texture analysis.” Prior honors included the Humboldt Award of the Alexander von Humboldt Foundation in Germany (1979); Doctor of Technology honoris causa from Tampere University of Technology, Finland (1982); Senior Scientist Award from the Japan Society for the Promotion of Science (1985); and fellow of the Minerals, Metals, and Materials Society (1987) and of the American Society for Metals (1993). He held visiting professorships at the Technische Hochschule (RWTH) Aachen, Germany (1971/72, 1979); McMaster University in Hamilton, Canada (1978); and McGill University in Montreal, Canada (1982).

    Fred retired from Los Alamos in 1999 and moved to Colorado, where he pursued an interest in neuroscience and the philosophy of the human mind. Later, he and his wife Marianne continued their lifelong “go West” migration — from Germany, to Boston, to the Midwest, to the Southwest — and finally settled in La Jolla, California, in proximity to one of their daughters. At the University of California, San Diego, he was a distinguished professor affiliate in the Department of Mechanical and Aerospace Engineering of the Jacobs School of Engineering.

    At the end of his life, he often talked about the good life he led, his love of his family, and the many great walks he took, as well as skiing in the mountains of Colorado, well into his eighties. He enjoyed the sunsets over the Pacific Ocean with his wife. Fred had a passion for collaboration, communication, and lively debates; with his wife, who had been instrumental in establishing the Host Committee for Foreign Visitors at Argonne, he drew together a worldwide community of scientists. He will be missed, especially when it is time for a good, fiery discussion on just about anything.

    Fred is survived by his wife, his four children and their partners, and six grandchildren.

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    1Kocks UF. 1966. A statistical theory of flow stress and work hardening. The Philosophical Magazine 13(123):541-566.
    2Kocks UF. 1970. The relation between polycrystal deformation and single-crystal deformation. Metallurgical Transactions 1:1121-1143.
    3UF Kocks, Argon A, Ashby MF. 1975. The Thermodynamics and Kinetics of Slip. Progress in Materials Science 19, Chalmers B, Christian JW, Massalski TB, eds. Pergamon Press.
    4Mecking H, Kocks UF. 1981. Kinetics of flow and strain-hardening. Acta Metallurgica 29(11):1865-1875.
    5Follansbee PS, Kocks UF. 1988. A constitutive description of the deformation of copper based on the use of the mechanical threshold stress as an internal state variable. Acta Metallurgica 36(1):81-93.
    6Kocks UF, Mecking H. 2003. Physics and phenomenology of strain hardening: The FCC case. Progress in Materials Science 48(3):171-273.