Decrease In Number Of Defects Research Articles

Thermally induced structural transformations and their effect on functional properties of Fe89.8Ni1.5Si5.2B3C0.5 amorphous alloy

The influence of thermal treatment on microstructure and functional properties of Fe89.8Ni1.5Si5.2B3C0.5 amorphous alloy and their mutual correlations were studied. Structural transformations were identified using DSC and characterized using X-ray diffraction. The alloy was found to exhibit a wide supercooled liquid region before crystallization, while kinetic parameters of observed structural transformation indicated high complexity of these processes, involving simultaneous movement of large groups of atoms. Investigation of magnetic and electrical properties of the alloy showed that structural relaxation prior to crystallization affected both magnetic susceptibility and electrical resistivity of the alloy, leading to an increase in both, which can be correlated to a decrease in number of defects and an increase in free volume in the alloy sample, enabling greater mobility of magnetic domain walls, but also decreasing electron density of states at the Fermi level.

Influence of structural transformations on functional properties of Fe75Ni2Si8B13C2 amorphous alloy

The influence of thermal treatment on functional properties of Fe75Ni2Si8B13C2 amorphous alloy was investigated, showing the change that resulted from thermally induced structural transformations. Thermal history of the sample was found to have a significant effect on magnetic properties. Structural transformations were identified using DSC and thermomagnetic curve and characterized using Mössbauer spectroscopy and X-ray diffraction. Further investigation of magnetic and electrical properties of the alloy showed that structural relaxation prior to crystallization affected both magnetic susceptibility and electrical resistivity of the alloy, leading to an increase in both. This was caused by a confluence of stress relieving and a decrease in number of defects and an increase in free volume in the alloy sample, not only enabling greater mobility of magnetic domain walls, but also decreasing electron density of states at the Fermi level. Annealing at temperatures below crystallization caused an increase in magnetic susceptibility of the alloy at room temperature, however, a shift in Curie temperature was not observed. The alloy also exhibits a wide supercooled liquid region before crystallization, where its functional properties remained relatively constant, exhibiting the low values of both magnetic susceptibility and electrical conductivity.

Effects of Crown Release on Growth and Quality of Even-Aged Red Maple Stands

Abstract The effects of six crown-release treatments on growth and bole quality of 54 dominant, codominant, and intermediate red maples (Acer rubrum L.) were examined in an even-aged stand in upper Michigan. Treatments included an unreleased control, a single-tree and a two-tree crown release, and a full crown-to-crown release of 5, 10, and 15 ft. Twenty-two years after treatment, all trees showed a decrease in number of defects. Trees released to 15 ft lost twice as many defects as unreleased trees. Codominants and intermediates lost twice as many defects as dominants. Overgrown knots were the most common defects and showed the greatest decrease over time. The number of epicormic branches also declined; dominants had no epicormic branches after 22 years. Growth was greater for all released trees than for unreleased trees. Twice as much growth occurred in the 15-ft treatment as in the control, but this result was not significantly greater than those of the 5- or 10-ft crown release treatments. Dominant trees grew significantly more than the intermediate trees. Twenty-two years after treatment, dominants appeared to be least affected by crown-release but had the fewest defects and largest diameters. Crown-release treatment had the greatest effect on intermediates. To maximize growth and maintain bole quality, a crown release of between 5 and 10 ft is recommended for red maple pole-size trees in the Lake States.

Fracture behavior and morphology of spun collagen fibers

The influence of gultaraldehyde (GA) crosslinking, basic chromium sulfate (Cr) tanning, and thermal treatments on the fracture behavior and morphology of spun collagen fibers has been studied. The fracture morphology of the fibers is characterized by longitudinal splitting along the fiber axis. Although the essential fracture morophology was not influenced by GA crosslinking, Cr tanning, and thermal treatments, the process of splitting depended on the kind of crosslink. Noncrosslinked and Cr-tanned fibers were split into fibrils, but GA-crosslinked fiber was split without fibrillation. The thermal treatments have two effects : One is decrease in number of defects and/or flaws ; the other is gelatinization. In the thermal treatment above 140°C, the gelatinization plays a more important role for the tensile properties than does the effect of a decrease of a defect. Gelatinization results in the enhancements of slippage and separation of macrofibrils and/or fibrils after the yield point.

Fracture behavior and morphology of spun collagen fibers

The influence of gultaraldehyde (GA) crosslinking, basic chromium sulfate (Cr) tanning, and thermal treatments on the fracture behavior and morphology of spun collagen fibers has been studied. The fracture morphology of the fibers is characterized by longitudinal splitting along the fiber axis. Although the essential fracture morphology was not influenced by GA crosslinking, Cr tanning, and thermal treatments, the process of splitting depended on the kind of crosslink. Noncrosslinked and Cr-tanned fibers were split into fibrils, but GA-crosslinked fiber was split without fibrillation. The thermal treatments have two effects: One is decrease in number of defects and/or flaws; the other is gelatinization. In the thermal treatment above 140°C, the gelatinization plays a more important role for the tensile properties than does the effect of a decrease of a defect. Gelatinization results in the enhancements of slippage and separation of macrofibrils and/or fibrils after the yield point. © 1996 John Wiley & Sons, Inc.