Memorial Tributes Volume 22 (2019) / Chapter Skim
Currently Skimming:
JOHN W. CAHN
JOHN W. CAHN
Pages 37-44
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 38... ...
His contributions to physical metallurgy and materials science and engineering, condensed matter physics, and mathematics are numerous and profound. John Cahn was born Hans Werner Cahn on January 9, 1928, in Köln, Germany, to Lucy Schwartz, a medical X-ray technician, and Felix Cahn, a Jewish lawyer who actively opposed the Nazis.
|
From page 39... ...
In 1954 John joined the Metallurgy and Ceramics Department at the GE Research Lab, where he was influenced by and collaborated with David Turnbull, John Hilliard, Ed Hart, and others. He was hired to perform experiments, but his lab was under construction so he had two years to roam the halls, discuss ideas with other staff, study, and focus on theory.
|
From page 40... ...
These topics included cellular and eutectoid precipitation at grain boundaries, the stereology of microstructure, and interface migration, including impurity drag. In a series of papers with John Hilliard, he developed the theory of nonuniform systems and formulated a nonclassical chemical diffusion equation that included a fourth derivative of concentration with respect to distance, the Cahn-Hilliard equation.
|
From page 41... ...
He permanently joined NBS as a scientist in the Center for Materials Science in 1979 and was named one of three initial Senior NBS Fellows in 1984. At NBS/NIST, John's eclectic range of research topics expanded to areas such as critical point wetting and diffusioninduced grain boundary migration as he continued work on the effect of stress on phase transformations, grain boundary
|
From page 42... ...
His detailed description to Dan Shechtman on the experimental rigor necessary to "prove" the existence of quasicrystals embodied this awareness as he and Shechtman challenged long-established laws of crystallography. As a consequence, the announcement of quasicrystals in late 1984 was met by "immediate worldwide acceptance, excitement, and confirmation" by the scientific community, as evidenced by the special session on quasicrystals at the American Physical Society's March meeting in 1985, a special symposium at the fall meeting of the Metallurgical Society
|
From page 43... ...
The team responded by creating seminal work on structural and compositional ranges over which quasicrystals existed, discovering new classes of quasiperiodic structures, developing a six-dimensional approach to understanding "quasicrystallography," formulating new approaches to simplify working with six-dimensional structures, and much more. John's vigorous defense of quasicrystals against public attacks by Linus Pauling was based on the underlying science and experimental evidence, and was quickly substantiated as the field of quasicrystals grew.
|
From page 44... ...
John had a brilliant mind and a warm heart. In addition to his own research, he stimulated, motivated, and mentored scientific colleagues at NIST and all over the world.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.