Brittle fracture in iridium |
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Authors: | S S Hecker D L Rohr D F Stein |
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Affiliation: | (1) Los Alamos Scientific Laboratory, 87544 Los Alamos, NM;(2) Michigan Technological University, 49931 Houghton, MI |
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Abstract: | Brittle fracture in fcc metals is uncommon. It is not common knowledge that single crystals of iridium, a high melting point
fcc metal, fail by brittle cleavage at room temperature. Furthermore, polycrystalline iridium fails predominantly by brittle
inter granular fracture at temperatures below 1000°C. With the aid of several models of brittle fracture we have demonstrated
that cleavage in iridium is intrinsic, resulting from apparently very strong and directed atomic binding forces. Intergranular
fracture in iridium has been generally assumed to arise from the segregation of harmful impurities to the grain boundaries.
We were able to demonstrate using Auger electron spectroscopy that impurity segregation to grain boundaries in iridium was
not necessary for grain boundary fracture to occur, thereby demonstrating that intergranular brittle fracture in polycrystalline
iridium is also intrinsic and not impurity related. |
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