2013 Volume 62 Issue 2 Pages 66-69
It has been recently pointed out that Alloy690 has the potential to become long-range ordering (LRO) of intermetallic compounds such as Ni2M after long-term use in service conditions in nuclear power plants. However, it is quite difficult to experimentally evaluate the influence of the LRO of Ni2M on SCC susceptibility. In the present study, authors developed the Ni2M-stabilized alloy with excessively enhanced phase stability of Ni2M based on the chemical composition of Alloy690. It was isothermally heat treated for up to 10000 h at 500℃ and 550℃. Microstructure observation, X-ray diffraction analysis and Vickers hardness test were subsequently conducted, and the results were compared with those of Alloy690. The Vickers hardness was significantly increased only in the Ni2M-stabilized alloy after isothermal heat treatment over 1000 h at 500℃. The results of TEM analysis suggest that it may be caused by the LRO of Ni2M. The influence of the LRO of Ni2M on SCC susceptibility will be investigated by the samples obtained in the present study.
