Microstructure and Properties of Tb₂TiO₅-Dy₂TiO₅ Neutron Absorber Material

Tb₂TiO₅-30wt%Dy₂TiO₅ neutron absorber material was prepared by high energy ball milling, cold isostatic pressing and high temperature sintering with Tb₄O₇ powder, Dy₂O₃ powder and TiO₂ powder as raw materials. The microstructure of the powder mixture at different ball milling time (0-48 h), and the microstructure, thermophysical properties and corrosion resistance of sintered bulks at different sintering temperature (1 200-1 400 ℃) for different times (1-96 h) were studied. The results show that the grain size of powder mixtures decreased with increasing ball milling time, and the homogeneous nanocrystalline powder mixture was obtained by ball milling for 12 h. Tb₂TiO₅-Dy₂TiO₅ bulks with high density and orthorhombic structure was obtained after sintering nanocrystalline powder mixture at 1 300 ℃ for 96 h. The thermal conductivity and thermal expansion coefficient at 500 ℃ were 2.2 W·m^-1·K^-1 and 5.8×10^-6 K^-1, respectively. The corrosion rate of the bulks in deionized water at 360 ℃/18.6 MPa almost kept a constant and the mean corrosion rate was 0.18 mg·dm^-2·h^-1. The prepared bulks had high thermal conductivity, low thermal expansion coefficient and good corrosion resistance performance, which was an excellent candidate as neutron absorber materials for control rods.