Mechanical behavior and microstructural evolution of vanadium alloys irradiated in ATR-A1

An irradiation experiment has been done in the ATR-Al to investigate irradi ation behavior of vanadium alloys in the low temperature regime from 200 de greesC to 300 degreesC with damage levels of 3 to 4 dpa. In creep measureme nts, creep tubes of V-3Fe-4Ti-0.1Si with inner pressures up to 165 MPa did not rupture during irradiation. The effective strain rate of creep was belo w 0.2% dpa(-1) and it showed the same tendency as V-4Cr-4Ti alloys. In Char py impact tests, all specimens of V-4Cr-4Ti-0.1Si and V-3Fe-4Ti-0.1Si showe d brittle behavior at room temperature and the DBTT increased to 60-150 deg reesC. The fracture surface showed cleavage. Tensile tests conducted both a t room temperature and at the irradiation temperature showed significant ir radiation hardening and brittle responses. TEM showed that high densities o f tiny defect clusters were formed in V-Cr-Ti and V-Fe-Ti alloys. Precipita tes could not be seen in specimens irradiated below 300 degreesC, however, fine defect clusters are considered to be the origin of brittle behavior in V-Cr-Ti alloys irradiated at low temperatures. (C) 2000 Elsevier Science B .V. All rights reserved.