Effect Of Microsegregation Research Articles

Effect of APB Microsegregation on the Strength of Ni3Al with Ternary Additions

ABSTRACTSolid solution strengthening for stoichiometric and non-stoichiometric alloys is studied using a microscopic model that takes into account the micro-segregation of the alloying additions and of the host atoms to antiphase boundaries. Experimental results for four ternary intermetallic compounds, Ni-Al-Si, Ni-Al-Ti, Ni-Al-Hf and Ni-Al-V, are analyzed in the light of the theoretical model. It is found that the athermal increment of yield strength for both stoichiometric and non-stoichiometric alloys can be explained using solid solution strengthening theory provided that the local concentration at the {111} antiphase boundaries between superpartial dislocations is used.

Effects of ferrite content and microsegregation on solidification crack susceptibility of duplex stainless steel weld metals

Effects of ferrite content and microsegregation on solidification crack susceptibility of duplex stainless steel weld metals

Mathematical analysis of solute redistribution during solidification based on a columnar dendrite model.

An exact solution and an approximate solution have been derived for the columnar dendrite model proposed by Ohnaka, 8) in which a solidification rate, equilibrium distribution coefficient and diffusion coefficient in solid are assumed to be constant throughout the solidification. By comparing with the exact solution, it has been shown that the approximate solution has good accuracy. Further the model is extended on the basis of the derived approximate solution by incorporating a thermal model of solidification. The extended model includes multi-component alloy accompanying phase transformation in solid and temperature dependence of diffusion coefficients, and excludes the assumption of a given solidification rate. The calculated results of the extended columnar dendrite model agreed well both with the available experimental data and the calculated results of the extended planar dendrite model proposed previously. The assumption of the solidification geometry is unimportant for quantifying the microsegregation effects.

The effect of microsegregation of the hydrogen solubility of palladium-rhodium alloys

The effect of microsegregation of the hydrogen solubility of palladium-rhodium alloys

高強度鋼の遅れ破壊におよぼすミクロ偏析の影響

高強度鋼の遅れ破壊におよぼすミクロ偏析の影響

The effect of shape variations during growth on the morphology ofin-situ eutectic composites

An experimental investigation has been conducted of the influence onin-situ eutectic composite microstructures of both gradual and abrupt changes in cross-sectional area, both with and without simultaneous changes in growth direction, and of the effects of changes in growth direction at constant cross-section. Alloys of the binary (Al-Ni and ternary Al-Cu-Ni) eutectic were chosen to eliminate the effects of microsegregation and these were grown under a variety of conditions of growth rate and temperature gradient, consistent with those used for off-eutecticin-situ composites, and in apparatus generally used for that work and described previously. As well as the expected variation in lamellae or inter-rod spacing with changes of cross-section, abrupt decreases in crosssectional growth area coupled with changes in growth direction produced a multigrain structure of various orientations. Potentially weak zones denuded of lamellae or rod growth were observed when the growth direction deviated beyond a limiting small angle at constant cross-section.

Effects of Micro-Segregation on the Inverse-Segregation in Copper-Tin Alloys

Effects of Micro-Segregation on the Inverse-Segregation in Copper-Tin Alloys

Microstructure and microsegregation effects in the intergranular corrosion of austenitic stainless steel

Intergranular corrosion in austenitic stainless steel was studied using transmission electron microscopy of corroded thin foils and electron probe microanalysis of bulk specimens. In the sensitized material, since carbides remained unattacked in corroded grain boundaries after exposure to a boiling copper sulfate-sulfuric acid solution, the location and severity of corrosion could be directly observed in relation to individual carbide particles for various precipitate morphologies. After the sensitized material was exposed to a potassium dichromate nitric acid solution, carbides were consistently absent from corroded grain boundaries as the particles themselves apparently became susceptible to attack in this environment. Chemical composition inhomogeneities were measured for nickel and chromium in the commercially annealed material and found to become more pronounced upon sensitization heat treatments. Such inhomogeneities can result in chemical composition differences across grain boundaries, which in turn can lead to electrochemical action that may adversely affect intergranular corrosion behavior.

冷延用ワークロールの肌荒れについて

A defect called“orange skin” of“rippling” is often found on the surface of work rolls of cold strip mill after 300-500 tons of steel strip have been rolled.We observed the roll surface by photo-and electron-microscope after these defects had developed.Also, we investigated the effects of hardness, micro-segregation, and microstructure on the wear of roll materials. The results are summarized as follows:(1) The cause of the defect formation is due to the microsegregation of roll surface.(2) In this case the segregation index Is, which shows the degree of micro-segregation, is about 1.4from the line analysis of Cr by EPMA.(3) To obtain higher homogeneity of the is lower than 1.2, the dendrite arm spacing after forging should be kept lower than 200. It is very difficult to obtain this condition.(4) We could expect that, if the segregation index is 1.1 or 1.2, the defect formed on roll surface will be avoided by homogeneous carbide distribution and higher hardness by adopting suitable heat treatment.

The Effect of Micro Segregation on the Observed Intensity in Thin-Film Microanalysis

AbstractIn the electron-probe microanalysis of thin alloy samples, particularly for areas which contain a high degree of solute segregation as are often obtained in extraction replicas or in electro chemically thinned foils, a correlation between the measured intensity and the sample microstructure has heen difficult to perform. The purpose of this study was to isolate the effect of micro segregation, i.e., segregation with respect to the beam size (∼2 μ) itself, on the characteristic intensity generated by a microvolurne. To accomplish this, a model system consisting of silver-powder particles (∼1 μ diameter) supported on an evaporated carbon film was investigated by using a thin-film microprobe accessory of an electron microscope (Hitachi HXA-1). The silver particles served as analogs to a highly concentrated segregation area, and the carbon film was analogous to the corresponding matrix. The simplicity of this system readily allowed for an analysis of the geometric positioning factor dependence of the generated intensity.It was observed that the intensity measured for a given particle could vary by as much as 1000% depending only on the relative position of that particle within the electron beam. This variation was derived to be due to both the distribution of electrons within the beam and the amount of mass occupied by the particle at each distance from the beam center. A computer program was developed to perform the necessary calculation to predict the relative intensity as a function of position within the beam. These calculated intensities were found to compare favorably with the experimental measurements.

The effect of microsegregation on the generation of dislocations in zinc single crystals

The applicability of Tiller's considerations on the production of dislocations is proved. The density of dislocations appearing during impurity microsegregation increases with increasing rate of growth as a consequence of the corresponding change in the effective distribution coefficient. The real value of ΔC at the microsegregation boundaries is at least twice as great as the average value of the concentration of impurities in the crystal in question.