| Popis: |
The influence of fast neutron irradiation (E > 1 MeV) at 600 K on the growth, mechanical properties and fracture toughness of Zr3Al-based alloys has been investigated for neutron fluences of up to 2.3 × 1025n/m2. The Zr3Al intermetallic grows under the influence of fast neutron irradiation. The irradiation growth exceeds 0.6 percent after a fluence of 2.3 × 1025n/m2, appears to increase linearly with fluence and shows no sign of saturation. The irradiation growth, which results in a dennty decrease, is recoverable by annealing at 773—973 K. Neutron irradiation influences the mechanical properties. In the 0 to 1025n/m2 fluence range there is a significant yield stress increase, a smaller increase in the ultimate tensile strength and a reduction in the plastic elongation. At fluences above 1025n/m2, there is a complete loss of ductility. The plane strain fracture toughness decreases from ~77 MPa · m12 for the unirradiated material to as low as 0.44 MPa · m12 at a fluence of 2.3. × 1025n/m2. The Zr3Al thus becomes as brittle as glass with neutron irradiation. The irradiation growth and loss of ductility are due to irradiation-induced disordering and the crystalline-to-amorphous transformation of the Zr3Al matrix. |
