(b. Willow Lake, South Dakota, 22 April 1888; d. Pittsfield, Massachusetts, 21 May 1965)
Jeffries graduated in mechanical engineering from the south Dakota school of Mines and Technology in 1910. His first employment was in 1911, as instructor at the Case school of Applied Science, Cleveland, Ohio. Inthe same year he became a consultant for the Aluminum Company of America and the General Electric company, beginning a lifelong association with these companies. His first research was the developement of new methods for the measurement of the grain size of metals and its relation to their properties. Industrial work on tungsten for electric lamp filaments led him to basic studies of secondary recrystallization and the role of inclusions, which he used as a thesis topic at Harvard (Ph.D., 1918) and which stimulated a decade of research on grain growth. In 1924-1926, with Robert S. Archer, Jeffries developed strong Aluminum alloys for casting and forging, exploiting the recently discovered phenomenon of precipitation hardening. This work led them to the slip- interference theory of hardening, the first theory of metal hardening to be based realistically upon crystal structure and was the immediate precursor of dislocation theory. Highly regarded by his professional colleagues for his combination of scientific theory and industrial realities, Jeffries served on many committees; and in his last years he took more pride in his managerial recommendations that enabled others to do research than in this own scientific accomplishments. The report of the committee under his chairmanship, “Prospectus on Nucleonics”(1944), was the first comprehensive study of the probable impact of nuclear energy on industry and society and served to trigger scientists’ wider concern in public affairs before the atomic bombing of Hiroshima.
I. Original Works. Jeffries’ writings include “Metallography of Tungsten,”in Transactions of the American Institute of Mining and Metallurgical Engineers, 60 (1919), 588-656; “The Slip Interference Theory of the Hardening of Metals,” in Chemical and Metallurgical Engineering, 24 (1921), 1057-1067; The Science of Metals (New York, 1924), written with Robert S. Archer; The Aluminum Industry, 2 vols.(New York, 1930), written with J. D. Edwards and F. C. Frary; “Autobiographical Notes of a Metallurgist,” in C. S. Smith, ed., Sorby Centennial Symposium on the History of Metallurgy (New York, 1965), pp. 109-119; and “Prospectus on Nucleonics”report of the Jeffries Committee to the Metallurgical Laboratory, Manhattan District, University of Chicago (Nov. 1944), classified material published in part in A. K. Smith, A Peril and a Hope (Chicago, 1965), app. A, pp. 539-559.
Many of Jeffries ’ professional papers have been deposited with the American Philosophical Society, Philadelphia.
II. Secondary Literature. A biographical article by C. G. Suits and a list of publications will appear in Biographical Memoirs. National Academy of Sciences (in press). A full biography of Jeffries written by William Mogerman is to be published by the American Society for Metals (Cleveland, in press).
Cyril Stanley Smith