NIELS HANSEN (1933-2021)

BY DARCY A. HUGHES AND DAVID J. SROLOVITZ

NIELS HANSEN made key advances in our knowledge of the mechanical and physical properties of metals and alloys, as well as of the evolution of deformation microstructures across length-scales and in multidimensions, as head of department at Risø National Laboratory, Denmark. He died on Aug. 19, 2021, at age 87.

Niels was born on Dec. 2, 1933, to Else Margrethe (Andersen) and Knud August Hansen in Helsingør, Denmark, the younger of two sons. As a teenager he set up a chemistry lab in the family basement using both his allowance and earnings from odd jobs. On bicycle he delivered the post to the far and hilly reaches of Helsingør and later worked at that city’s shipyard, electroplating and treating corrosion. In his basement laboratory, he and a fellow chemistry student invented, produced, and sold a powder to clean the ubiquitous chalk deposits caused by Danish well water. By the time his mother disposed of the worrisome laboratory in the family basement, he had gained and helped to equip a new one, thanks to the growing worldwide interest in atomic energy.

Niels earned a five-year degree from Den Polytekniske Læreanstalt (now Danish Technical University (DTU)) in civil engineering, with a specialization in chemistry, in 1957. After graduation, he reported for service to the Navy. The Navy quickly sent him to fill the need for metallurgical engineers at the new Atomic Energy Commission Research Establishment, Risø, Roskilde, Denmark. (Over Niels’ 60-year career, the name changed to Risø National Laboratory, or Forskningscenter Risø, and then to Risø Campus, DTU in 2012.) Risø sent him to Paris to earn a Diplome d’Études Approfondies at the Institut National des Sciences et Techniques Nucléaires (1958). His complete immersion in post-war France and its language offered his first taste of international science. Lectures in French were the sole source for passing exams, the students were friendly but competitive, and his small apartment at the foot of Montmartre was cold.

Time in Paris was soon contrasted with post-war United States. He disembarked from his north Atlantic crossing, took a flight, and stepped off the plane to meet summer in North Carolina wearing heavy Danish wool clothes and a salt-stiff coat. He soon became at ease, however, with new colleagues in the General Electric Nuclear Energy Division — no doubt because of his curious nature in both scientific research and people as well as his optimistic enthusiasm. He improved his English, developed an unchanging love of the United States, and practiced his notion that when you come from a small country, you need to make friends, not enemies.

Back in Denmark, Niels began the first phase of his career during an era when the creation of and need for new alloys were surging. Spurred by his international travels, he and his burgeoning group experimented with powder metallurgy to produce new dispersion-strengthened alloys for nuclear power reactors. Niels authored or co-authored five patents. Four of these patents and seven single-author publications comprised the highest-level degree of Doctor Techniske at Den Polytekniske Læreanstalt (later DTU) in 1971. With his usual energy, he also juggled serving as head of the Metallurgy Department at Risø in 1964 and lecturing part time at DTU (1961-97), not to mention meeting his future wife Annette Faber Bierfreund through his brother’s law class and then marrying her in 1964.

In the second phase of his career, his leadership and vision enabled the department to expand its technology and research across the field of materials science with about 100 engineers, scientists, and technologists. Growth was paradoxically accomplished against a background of declining social acceptance of nuclear power in Denmark. His developing university affiliations in Britain drew his attention to basic research. Strength and microstructure of polycrystals remained a strongly explored theme in his research group, leading to key contributions to the work-hardening of metals, including the development of a now widely accepted framework for the quantitative description of deformation microstructures in metals, succinctly summarized in his 2001 Robert Franklin Mehl Award lecture, “New Discoveries in Deformed Metals.” As part of this work, Niels also strongly advocated for the development of emerging technologies for in-situ testing and characterization, for example, neutron diffraction, automatic electron backscattered diffraction to a three-dimensional synchrotron, and laboratory-scale X-ray diffraction. Conferences at the Battelle Memorial Institute inspired Niels to initiate in 1980 the first of the yearly Risø International Symposiums on Materials Science. The 42nd and most recent conference was held after his death in 2022. These conferences attracted scientific collaborations with universities and national laboratories across the globe, especially with the United States.

On his birthday in 2000, he retired according to rules on age. To stop working and writing on science was unthinkable to him, and Niels volunteered as a senior scientist at Risø to guide students and contribute to the research, publications, and grant applications until 2019. He continued his collaborations in the United Kingdom and the United States and expanded relationships with universities in China as the Cold War began to cool in 1995. The latter included month-long visits to China and occasionally Japan until he was 85 years old; the majority of his time was spent discussing and working with graduate students and providing guidance to junior faculty members. Many students and postdoctoral fellows performed research at Risø through collaboration with Niels and later became professors. His discipline and enjoyment of science writing resulted in 293 publications with an H factor of 70.

Apart from science he also read his youthful favorites, Jacobsen, Steinbeck, Dumas, Turgenev, and Dostoyevsky, aloud to his wife while she was sick. Niels enjoyed art, especially modern and contemporary art, and was a member of the Risø art club. Members raised money to purchase art from young Danish artists they knew. Prints, paintings, and sculptures added to the creative and supportive atmosphere in the laboratories. He kept his kayak ready in his garden, where he created framed views by maintaining his best trees. In his garden, he realized that a simple yearly summer grass cutting would balance the light and nourishment for seven species of bulbs that bloomed in succession throughout the spring. This style was mirrored in his approach to collaborative research and the nurturing of students so that they flourished. His questions brought clarity and simplicity to the work, enabling students and colleagues to extract the best essence from their research.

He was awarded Danish Knighthood (1978), the Poul Bergsøe Medal of the Danish Metallurgical Society (2000), and the Robert Franklin Mehl Award of the Minerals, Metals & Materials Society (2001). Several honorary positions were granted to Niels at home and around the globe: fellow of the American Association for the Advancement of Science (1956); member of the Danish Academy of Technical Sciences (1968); fellow of the Institute of Materials, UK (1973); honorary member, Metallurgical Society of France (1986); fellow of ASM International (1988); member of Academia Europaea (1993); foreign associate, National Academy of Engineering (1995); foreign honorary member, American Academy of Arts and Sciences (2005); honorary member, Japanese Institute of Metals (2007); Einstein Professor, Chinese Academy of Sciences (2011); and Research.com Materials Science in Denmark Leader Award (2022, 2023).

Niels Hansen is survived by his two nephews, Henrik and Jakob Hansen, and his nephews’ children. His wife, Annette, predeceased him in 2015. He will be greatly missed not only by his family but also by the many researchers he mentored and the broader community.