We studied the fabrication of functionally graded Al2O3–CeO2-stabilized-ZrO2 (CTZ) ceramics by spark plasma sintering. The ceramic composite exhibits a gradual change in terms of composition and porosity in the axial direction. The composition gradient was created by layering starting powders with different Al2O3 to CTZ ratios, whereas the porosity gradient was established with a large temperature difference, which was induced by an asymmetric graphite tool configuration during sintering. SEM investigations confirmed the development of a porosity gradient from the top toward the bottom side of the Al2O3–CTZ ceramic and the relative pore volume distributed in a wide range from 0.02 to 100 µm for the samples sintered in asymmetric configuration (ASY), while for the reference samples (STD), the size of pores was limited in the nanometer scale. The microhardness test exhibited a gradual change along the axis of the ASY samples, reaching 10 GPa difference between the two opposite sides of the Al2O3–CTZ ceramics without any sign of delamination or cracks between the layers. The flexural strength of the samples for both series showed an increasing tendency with higher sintering temperatures. However, the ASY samples achieved higher strength due to their lower total porosity and the newly formed elongated CeAl11O18 particles.
Continuing the earlier experiments, a series of new effects will be presented in this paper which demonstrate, that the amorphous Curie temperature ( T am C ) can be altered by resting the samples at low temperature such as (liquid N 2 , 77 K). The sign and magnitude of this shift depends on the alloy composition, but can also be influenced by the rate of liquid quench applied during the ribbon formation. T am C is lowered during liquid N 2 treatments for the binary Fe85B15 glass. The effect is the same when a small amount of Si is added to the Fe 85 B 15 . Exceeding the critical concentration limit of the Si, the sign of T am C changes.
The time dependence of dehydrogenation is investigated by the measurement of stress sensitive magnetic properties in FINEMET type alloys after various degree of amorphousnanocrystalline transformation. It was found that defect structure is dominantly responsible for the sensitivity to hydrogen absorption and desorption in this alloy, and the nanograin formation has only a minor significance in this respect.
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