Fritz Thümmler was born in Dresden, Germany, on 22 May 1924 where he also had his education. After finishing the high school in 1942, he started his diploma in chemistry at Technische Hochschule (TH), Dresden. He was drafted into the German army in June 1944 and continued to serve there till May 1945. He remembered to have survived the bombing of Dresden in February 1945 by accidentally leaving the city centre shortly before. After the war, he worked at British-American Tobacco Ind., Dresden, for two years, after which he finished his diploma in Inorganic Chemistry in 1948. From 1948 to 1954 he served as an Assistant and later Senior Assistant at the Institute for Materials Science of TH Dresden. In 1953 he finished his PhD thesis work in the field of Powder Metallurgy. From 1954 to 1956 he served as the Research Group Leader at Hartmetallwerk Immelborn (Thuringia). In 1956 he joined the Central Institute for Nuclear Physics Rossendorf as the Head of the Materials Department and worked in the field of nuclear fuel and cladding materials until 1961. In 1957 he got the postdoctoral lecture qualification in Materials Science (Dr.-Ing. habil.) with a thesis in the field of sintering.
In June 1961, a few weeks before the Berlin wall was erected, he left Eastern Germany with his family and took a position at the Max-Planck-Institut für Metallforschung, Stuttgart, as a Research Group Leader. He worked there until 1964, mainly in the field of nuclear materials. During that time, he was offered the position of Professor at Technische Hochschule (later University) Karlsruhe and the role of Director of the Institute for Materials Research at the Nuclear Research Center Karlsruhe. He accepted both positions and retired from the latter position in 1987.
In 1984, Fritz Thümmler was the driving force in founding a new institute, Ceramics in Mechanical Engineering, at Karlsruhe University. This unique institute provided a platform for 9 faculty members to cooperate in the field of ceramics materials, design and application. He served as the Acting Director of this institute from 1985 to 1990. In 1991 he retired as Professor Emeritus. For many years after his retirement, he stayed in close contact with the Institute for various programmes. In 2011, during the foundation ceremony of the Institute of Applied Materials in Karlsruhe, he was given the honour to deliver the keynote lecture on 45 years of materials research at the University and the Nuclear Research Center Karlsruhe.
During his tenure at the University, he taught basic and several advanced courses in Mechanical Engineering, Material Science and Technology, Powder Metallurgy, Ceramics and in Materials for Nuclear Technology.
Fritz Thümmler authored or coauthored more than 300 articles on Powder Metallurgy and on Engineering Ceramics in several scientific and technical journals. He also authored or co-authored several books on Powder Metallurgy and Reactor Materials. His 15 patents on ceramic fuels, hard metals and sintered steels highlight the economic significance of his work.
He was an active member of the scientific community holding positions like President of Plansee-Gesellschaft für Pulvermetallurgie, Reutte/Tirol (1971–1974), Chairman of Ausschuss für Pulvermetallurgie, Düsseldorf, (1973–1981), Deputy Chairman of Wissenschaftlich-Technischer Rat des Kernforschungszentrums Karlsruhe (1979–1982), Member of the Board of Deutsche Gesellschaft für Metallkunde (1979–1980), Co-Editor of Journal of Nuclear Materials, Amsterdam (1966–1984) and Fellow of the Institution of Metallurgists, London (1969). He received numerous awards during his lifetime, among which the Federal Cross of Merit (1985) and the Skaupy-Award (1987) merit a mention.
Fritz Thümmler was highly respected by his students and co-workers, and they thoroughly enjoyed his company. He was associated with his former institutes until the end of his life on 5 February 2022. He lived a long, successful and fulfilling life with his wife Ursula in Karlsruhe. He is survived by his wife, one daughter, two sons and their families. Fritz Thümmler was laid to rest at the Cemetery of Karlsruhe-Grünwettersbach, where he lived as a respected and socially and culturally engaged community member.