| Abstract |
| A lattice variation with ordering treatment at 400 ℃ in Alloy 600 was systematically investigated using neutron diffraction. Alloy 600 was water-quenched, air-cooled, and furnace-cooled from solution anneal- ing treatment at 1095 ℃. These were ordering-treated up to 5,500 hours at 400 ℃. The results showed that the magnitude of lattice contraction depended on the cooling rate and decreased with the cooling rate. This is due to the fact that the number of ordering bonds increases with decrease in cooling rate. The lattice contraction appeared to be anisotropic according to the crystallographic planes. The water quenched specimen showed a maximum lattice contraction up to 0.04% in the {111} and {200} planes, and this was saturated after 2,000 hours. The lattice contraction due to the ordering reaction should be considered in the assessment of integrity in components made of Alloy 600, because the ordering reaction is a spontaneous and unavoidable phenomenon below 520 ℃ in the Alloy 600. |
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| Key Words |
| Alloy 600, cooling rate, ordering reaction, neutron diffraction, lattice contraction, solution anneal |
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