FeN phase generation has been observed by x-ray analysis in FeTaN films, which normally show α-Fe, TaN phase, and no FeN phases. With a rise in substrate temperature Ts above 200 °C, FeN phases are generated in nitrogen reactive sputtering process with columnar structure formation, and remain after annealing. With FeN phase generation, coercivity Hc and magnetostriction λ values increase markedly. Moreover, internal stress σ for the films increases drastically. The FeTaN films, sputtered on low temperature substrate, generate no FeN phases, and show low Hc, about 0.1 Oe, and low λ. Consequently, FeN phase generation with columnar structure formation has negative effects for FeTaN films to be used as magnetic head core materials. For preparation of FeTaN films, the substrate temperature has to be controlled to a sufficiently low value for suppression of FeN phase generation.

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For 6061-T6 aluminum alloy plates with fine-or coarse-grained structure, SSRT slow strain-rate technique in humid air was carried out using a smooth or notched tensile specimen to evaluate the susceptibility to hydrogen embrittlement and to demonstrate the hydrogen effect on fracture process. The fine-grained materials under the hydrogen environment showed little change in tensile properties compared with the inert environment of dry nitrogen gas, while the coarsegrained materials exhibited some change in ductility; namely a decrease for the smooth specimen and an increase for the notched specimen. Although the materials ruptured by ductile fracture independently of grain size, the characteristic feature that coarse slips and void formation were promoted by hydrogen was observed. It is therefore suggested that the nature of hydrogen effect in 6061-T6 alloys is an enhancement of ductile fracture. As the increase in grain size leads to encourage the hydrogen effect, the grain coarsening should be restrained.

For 6061-T6 and 7075-T6 aluminum alloy plates, SSRT slow strain-rate technique tests in humid air with 90% relative humidity were carried out using a notched tensile specimen to evaluate the susceptibility to hydrogen embrittlement and to appreciate the role of notch in the process of HEAC hydrogen-environment-assisted cracking. 7075-T6 showed a significant embrittlement due to intergranular cracking more inspired by the existence of notch, while in contrast, 6061-T6 exhibited a trend of an enhanced plastic deformation by hydrogen effects, accompanied with a trace of nonconventional TTS facet in fracture surface and an increase in notch opening displacement in the early stage of still low stress level. The SSRT behaviors of these alloys are explained to result from the mechanism of hydrogen-enhanced localized plasticity, where the process of hydrogen population is supported to include both effects of trapping at microstructural defects such as inclusions and stress-induced diffusion at macroscopic defects such as notch.

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