A replica technique for extracting precipitates from neutron-irradiated or thermal-aged vanadium alloys for TEM analysis

Abstract

A carbon replica technique has been developed to extract precipitates from vanadium alloys. Using this technique, precipitation phases can be extracted from neutron-irradiated or thermal-aged V–4Cr–4Ti alloys. Precipitate identification using EDS X-ray analysis and electron diffraction was facilitated. Only NaCl type of Ti(OCN) precipitate was formed in the thermal-aged V–4Cr–4Ti alloys at 600°C for 20h and cation sub-lattice was only occupied by Ti atoms. However, the thin plate of precipitates with NaCl type of crystallographic structure could be seen in the V–4Cr–4Ti alloys irradiated at 593°C in the JOYO fast reactor. The precipitate contained chromium and vanadium atoms on the cation sub-lattice as well as titanium atoms. It is considered that the phase of MX type (M=Ti, V, Cr and X=O, N, C) is a metastable phase under neutron irradiation.