1993 年 34 巻 11 号 p. 1130-1136
High-purity molybdenum single crystals with the antitwinning axial orientation were irradiated with 14 MeV neutrons at room temperature, 473 K and 673 K under low neutron fluences of (2.1∼2.7)×1021 n/m2 using the Rotating Target Neutron Sources (RTNS-II), and then were deformed in tension at 290 K. The irradiations led to the inhomogeneous yielding accompanied by large yield drops. The active slip plane, which of the unirradiated specimen was the plane (\bar101), was shifted more and more towards the maximum shear stress plane (\bar211) with decreasing irradiation temperature. By the isochronal annealing, the pronounced yield drop disappeared above 973 K. Furthermore, the flow stress of the specimens irradiated at room temperature changed from softening to hardening near 500 K and the strain-rate sensitivity also responded to this change, which was related to the migration of vacancies. Especially for the specimens irradiated at 673 K, it was found that the irradiation effects still remained above 973 K.
