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produce amorphous material—until a
few years later when x-ray diffraction
showed that no matter how far grains
are distorted, they still retain their
crystalline structure. As late as 1924,
Jeffries could find no solution to grain
boundaries other than the amorphous
cement theory.
Jeffries took another consulting
assignment at the Aluminum Casting
Co. The company was having problems
with casting defects in parts being ex-
ported to countries allied against Ger-
many in WWI. Even though the compa-
ny was partially owned by Alcoa, they
did not have the knowledge to help
their customers with technical prob-
lems. This work led to Jeffries’ expertise
in aluminummetallurgy.
In 1917, he ended his teaching ca-
reer and enrolled in a graduate program
at Harvard University under Albert Sau-
veur. Jeffries spent a year in residency
at Cambridge with his family, though it
was an unusual time for him to leave his
consulting practice with the war going
on. He then returned to Cleveland to
finish his degree by publishing his work
“Grain Structure in Metals.”
ALLOY DEVELOPMENT
In 1920, Alcoa acquired the Alumi-
num Casting Co. laboratory for nonpay-
ment of aluminum purchases, so Jef-
fries was now a consultant to Alcoa. He
was joined by Robert Archer, a recent
chemical engineering graduate from
the University of Michigan. Jeffries and
Archer worked on improved alloys for
forging and casting during the 1920s,
sharing patents and papers on all their
work. During this time, they invented
casting alloys using 5% and 7% silicon
(355 and 356), an aluminum-copper
alloy (195), an aluminum-magnesium
alloy (220), and an automotive piston
alloy (132) containing 12% silicon. Their
new forging alloys included adding
0.75% silicon to Duralumin (14s) and
a copper-free alloy containing magne-
sium and silicon (25s). Alloy 25s would
be used to make aircraft propellers
during WWII. Jeffries and Archer shared
in 10 patents and 13 published papers
during this decade, and coauthored the
book The Science of Metals in 1924.
This assignment, along with his
work at General Electric, lasted through-
out the 1920s. Jeffries was joined by
many new metals researchers who
would train under him and make a rep-
utation of their own in later years. One
of these associates was Edgar Bain, who
worked with Jeffries on problems with
high-speed tool steels that failed during
the drawing of tungsten wire. They pub-
lished a research paper on slip interfer-
ence by alloy carbides for the secondary
hardening of these steels. This theory
was accepted until it was refined when
dislocations were discovered to be the
mechanism for plastic deformation.
Jeffries remained at Alcoa until
1936 when he left to assume full-time
duties at General Electric. Of all the years
heworkedat Alcoa, itwas just apart-time
assignment while he continued to serve
as a consultant at General Electric. This
dual arrangement provided him with an
incomewell abovemost engineers of the
time. His new full-time career at General
Electric included primary responsibility
for developing a commercial business
in tungsten carbide tools. This was an
area of technology that interested Jef-
fries after Samuel Hoyt showed him that
the new tungsten carbide tooling could
solve the problem of machining the new
high-silicon piston alloy. Tungsten car-
bide later became a tool material that
was ideal for severe machining applica-
tions and Jeffries played a large role in
promoting this business into a major in-
dustry. After WWII, Jeffries was appoint-
ed a vice president of General Electric’s
new chemical division.
AWARDS AND HONORS
Among Jeffries’ many awards are
ASM’s Albert Sauveur Achievement Award
in 1935, ASM’s first Gold Medal Award in
1943, and the prestigious John Fritz Med-
al in 1946. He was elected to the National
Academies of Science, Engineering Divi-
sion in 1939, and served as a consultant
to Arthur Compton during WWII on the
Manhattan Project. For his wartime work,
Jeffries was awarded the Medal for Merit,
the highest civilian honor by the U.S. gov-
ernment. During his active career, Jeffries
played leading roles in several technical
organizations, including serving as presi-
dent of the American Society for Metals in
1929. Among his peers, Jeffries was con-
sidered the elder statesman of American
metallurgy. After retirement, he served
as chairman of the ASM World Congress
in 1951 and again in 1956. Jeffries died of
cancer in 1965 at age 76.
For more information: Charles R. Simcoe
can be reached at .
Automotive engine pistons, cross-sec-
tional view. Jeffries and Archer devel-
oped an aluminum-silicon alloy used in
auto engines since the 1920s. Courtesy
of Mj-bird, Wikimedia Commons.
Jeffries and Archer developed a forging alloy for propellers used on WWII aircraft, such as the
Republic P-47N Thunderbolt shown here. Courtesy of U.S. Air Force.