Gallery 2
Paul E. Danielson
"I have been driven with a passion and fire in metallography for 46
years," says PAUL E. DANIELSON of the Department of Energy's Albany
Research Center in Oregon, where much of his work has focused on
characterizing metals used in power generation plants. Some of his most
striking micrographs come from analyses of titanium, but he has worked
with an enormous diversity of metals and alloys. "It often is beautiful
art," Danielson says, "but it also helps my customers better understand
what's going on with their materials."
Image 1, used also on the cover of the May 15 issue of Chemical
& Engineering News, depicts flaws in a weld joining two
titanium sheets. The dark blotches are voids where gas bubbles formed,
and the blue region is associated with unwanted and bond-weakening
reactions with oxygen and nitrogen. The following five images are also
from titanium specimens. Image 2 shows both the long and smaller
equiaxed grains that emerged when a piece of titanium sheet was
cold-worked, probably through rollers, to strengthen it. Image 3, of
cast titanium, relies on an optical technique to show impurities lining
up in bands in the metal's grains. A different optical technique
highlights the grains and phases of another piece of cast titanium in
Image 4. Image 5 shows what happens internally when a cast-titanium
ingot is forged into other shapes. Image 6, the last titanium image, is
from a 22-mm-thick plate with grains made colorful with the use of
polarizing filters. Images 7–9 show the internal structure and
beauty of, respectively, cast vanadium, cast zirconium, and stainless
steel.
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