The yield strength of a series of neutron-irradiated iron-gold alloys was found to be significantly higher than a similar series of iron-copper alloys that were irradiated at the same fluence and irradiation temperature. An atom probe field ion microscopy and transmission electron microscopy characterization of these alloys has been performed. Atom probe analysis revealed significant depletions of copper and gold in the matrices after neutron irradiation. High number densities of small coherent zones on the thesz100theszα planes were observed by both transmission electron microscopy and field ion microscopy. A maximum gold concentration of ∼ 4 at% Au was found in the coherent zones for material neutron-irradiated at 290°C to a fluence of ∼ 1.2 × 1023nm−2.

The orientation relationship between lath martensite and the narrow films of retained austenite in low carbon, low alloy steels has been determined to an accuracy of approximately ±12° using Kikuchi line patterns obtained with a 7 nm probe in a 200 kV STEM set up for microdiffraction. The mean of the orientation relationship determinations was close to the Greninger-Troiano relationship with the extreme results showing a spread of ±2° and lying between the neighbouring Kurdjumov-Sachs and aishiyama-Wassermann relationships. Laths with the same habit plane formed packets and, in general, adjacent laths in such a packet were of the same orientation. However a few cases were observed where adjacent laths had markedly different orientations. In all these cases the two orientations represented a pair of orientation relationship variants in which the same close packed plane in the austenite was parallel to a close packed plane in the martensite and the same close packed direction in the austenite was approximately parallel to a close packed direction in the martensite, i.e. (111)γ nearly parallel to (101)α[1110]γ 1.5 to 3° from [111]α and (111)γ nearly parallel to (101)α[110]γ 1.5 to 3° from [111]α.

Specimens of perovskite (CaTiO3) irradiated with fast neutrons have been examined by X-ray diffraction. Expansion of the unit cell was anisotropic. The volume expansion increased with dose and approached a saturation value of 3.8%. X-ray diffraction lines showed both broadening and attenuation. The attenuation could be explained by postulating random atomic displacements, akin to thermal disorder, having an r.m.s. magnitude of ~ 0.02 nm. Recovery of the lattice parameters takes place in the temperature range 300–900°C, with a spectrum of activation energies. Effective activation energies of 2.52 ± 0.08 and 3.73 ± 0.13 eV were observed during the early and middle stages of recovery.

Dislocation loops formed in high-purity titanium irradiated at 673 K to 3.9 × 1023 neutrons/m2 (> 1 MeV) have been characterized using transmission-electron-microscopy techniques. The loop Burgers vector was of the form 1/2〈1120〉 and loop-normal measurements showed considerable deviation from the pure edge orientation. The loops were invariably elliptical with the major axis approximately parallel to the [0001] direction and the minor axis in the (0001) plane. Vacancy loops were predominant, but after allowing for the larger size of interstitial loops, the numbers of vacancies and interstitials stored in loops were found to be approximately equal.

A transmission electron microscope (TEM) was used to study the neutron irradiation-induced defect structures in zirconium from various sources irradiated to fluences up to 1.3 × 1025 neutrons (n)/m-2 > 0.1 MeV and temperatures in the range 478 to 823 K. Below 673 K the predominant form of damage consists of ⅓ 〈1120〉 dislocation loops. At higher irradiation temperatures, depending on specimen purity, the defects may include faulted ⅙ 〈2023〉 loops and voids in addition to the perfect ⅓〈1120〉 loops. The temperature regime of the stability of the various defects was defined. Quantitative measurements showing the effect of irradiation temperature and specimen purity are presented and discussed.

The results are given of an international “round-robin” experiment to study the nature of the damage structure in neutron irradiated zirconium and zircaloy-2 using transmission electron microscopy. The damage structure consists entirely of 13α<112̄0> dislocation loops and no evidence has been found for c-component loops. Both vacancy and interstitial loops were found in specimens irradiated at 400 °C, with an excess of vacancy loops. Quantitative measurements of loop size distributions and loop concentrations are reported. All specimens exhibited “corduroy” contrast to varying degrees. The importance of choice of imaging conditions to minimize the contrast from thin foil artefacts such as oxide films and surface hydrides is stressed. The significance of the results is briefly discussed with reference to current theories of irradiation growth.

The nature of the damage structure in neutron-irradiated zirconium has been studied using transmission electron microscopy. The damage structure consists of dislocation loops with a/3⊂112̄0〉 Burgers vectors. No evidence was found for c component dislocation loops. The dislocation loops are non-edge in character and are elliptical with the loop minor axis in the (0001) plane and the major axis in the vicinity of the [0001] direction. This ellipticity was particularly marked for large vacancy loops whereas interstitial loops tended to be circular. Under all irradiation conditions studied, the loop populations were mixed interstitial/vacancy.