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An HVEM study of displacement cascade damage in Nb/sub 3/Sn at 13 K
TEM images of the martensite structure in Nb/sub 3/Sn were recorded at various temperatures between 12 and 30/degree/K. The transition to the superconducting state was observed by a slight deflection of the electron beam due to a perturbation of the magnetic field of the objective lens at the sample. The primary interest is in irradiation effects due to fast neutrons from a fusion reactor, and therefore ion irradiation conditions that are somewhat comparable to this were selected. These consisted of 50 keV Xe/sup /plus// irradiations to simulate neutron produced cascades in a near surface region and 1.5 Mev Kr/sup /plus// to produce cascade damage through a greater sample thickness. Defect images were obtained as a function of ion dose at 13/degree/K using both fundamental and superlattice dark-field reflections in two-beam conditions. For 50 keV Xe/sup /plus// irradiations at 13/degree/K the defect yields were quite low at low ion doses where individual defect cascades are well separated. At higher ion doses when significant cascade overlap is present, defect density and contrast became greater than expected. Annealing to room temperature produced a large increase in defect density. Irradiation by 1.5 MeV Kr/sup /plus// at 15/degree/K removed the martensite structure by an ion dose of 5/times/10/sup 12/cm/sup /minus/2/. Further irradiation to 3.5/times/10/sup 13/cm /sup /minus/2/ produced evidence for the initial stage of amorphization 24 refs., 3 figs