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A D V A N C E D M A T E R I A L S & P R O C E S S E S | N O V E M B E R / D E C E M B E R 2 0 1 5

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METALLURGY LANE

Metallurgy Lane, authored by ASM life member Charles R. Simcoe, is a continuing series dedicated to the early history of the U.S.

metals and materials industries along with key milestones and developments.

PIONEERS IN METALS RESEARCH—PART III

METALS PIONEER PAUL DYER MERICA AND HIS ASSOCIATES AT THE NATIONAL BUREAU OF STANDARDS

DISCOVERED THE PRINCIPLES THAT GOVERNED THE AGE HARDENING OF DURALUMIN.

D

uralumin, the Al-4Cu-0.5Mg alloy

invented by Alfred Wilm in the

early 1900s, was in production

during World War I in Germany, France,

and England. Germany built nearly 100

giant Zeppelins using duralumin for the

framework, while France and England

used it for limited aircraft parts. The U.S.

was behind in both military aircraft and

duralumin development, so it did not use

the alloy in these early days.

Duralumin was believed to be a

unique alloy, which could not be du-

plicated in any other alloy system.

The manner in which it aged to high

strength was a complete mystery. In

this atmosphere, the National Bureau

of Standards initiated a research pro-

gram to study the alloy’s behavior.

Paul Dyer Merica was selected to head

a small group of researchers studying

duralumin behavior during age harden-

ing. Results showed that aging in dural-

umin was not unique, but was the basis

for a new strengthening mechanism in

metal alloys that could be applied to

many alloy systems. The principle of

age hardening is widely considered the

most important metallurgical discovery

in the first half of the 20th century.

EARLY LIFE AND EDUCATION

Paul Dyer Merica was born in 1889

to Charles and Alice Merica. He was

raised and educated in Warsaw, Indi-

ana, and attended DePauw University

in Greencastle where his father had

preceded him some 20 years earlier.

After three years, Merica transferred to

the University of Wisconsin where he

received a degree in physics. He taught

physics at Wisconsin for one year and

then left the U.S. for two years to teach

at Zhejiang University in China.

After a brief return to the U.S. in

1911, he moved to Germany to enroll in

graduate studies at the Royal Institute of

Technology in Charlottenburg. Here he

was classmates with Samuel Hoyt, an

Americanwho had enteredmetallurgy at

Paul Dyer Mercia led the team that

discovered the principles governing

precipitation hardening.

The first major use of duralumin was in the

frame of the Zeppelins built in Germany for

bombing London during World War I.

A wrecked Zeppelin brought down by British aviators near the coast of Essex, September 23,

1916.

Columbia University in a course taught

by William Campbell. What we know

about Merica during his time in Germany

was written by Hoyt in his book,

Men of