Short−range order in Au−Fe radiation−enhanced diffusion and the effectiveness of 14−MeV neutrons

Solute clustering in a Au−Fe (17% Fe) alloy has been demonstrated by Mössbauer effect measurements of the magnetic ordering temperature. Neutron irradiation at room temperature produces clustering by means of radiation−enhanced diffusion, while annealing at high temperatures is required to produce clustering thermally. The radiation−enhanced diffusion effect was used to compare directly the efficiency of mobile defect production by 14−MeV fusion neutrons and reactor neutrons. The 14−MeV neutrons are more effective by about a factor of 10 than the reactor neutrons (E≳0.1 MeV) in producing mobile lattice defects. Other compositions failed to respond to radiation−induced clustering, suggesting that Au−17−Fe is in a critical composition region regarding the response of the magnetic ordering temperature to variations in short−range order.