Effect Of Solute Additions Research Articles

Uncovering the influence of metallic and non-metallic impurities on the ideal shear strength and ductility of Ti: An ab-initio study

The mechanical properties of Ti alloys are significantly affected by the introduction of solute or impurity elements. Thus, the role of impurities on the hardening or softening behavior of α-Ti was investigated through first principles calculations. In particularly, to provide a comprehensive electronic and atomic basis of solute addition in α-Ti, the effect of metallic (V and Al) and non-metallic (C and O) impurities on the ideal shear strength (ISS) and generalized stacking fault energy (GSFE) across different slip systems of Ti were probed. The results revealed that the addition of V atom reduces both ISS and unstable stacking fault energy across various slip systems of α-Ti, whereas Al addition increases the ISS of Ti. Further, the addition of O atom decreases ISS for most of the slip systems while C solute atom increases ISS across all slip systems of α-Ti. To illustrate the underlying factors influencing the observed softening/strengthening behavior, the electronic density of states and valence charge transfer were determined. The electronic density of states calculations showed that the contribution from the d states of V atom decreases the stability of Ti-V solid solution, thereby leading to a decrease in the plastic anisotropy of α-Ti. Finally, the shearability parameter and critical resolved shear stress (CRSS) ratios across different slip systems of Ti solid solutions were calculated to understand the macroscopic effects of impurity addition on the deformation behavior of α-Ti at ambient conditions. Overall, the first-principles study provides an insight into the electronic basis of strengthening/softening effect of solute addition in α-Ti and assesses their implications on the deformation behavior of α-Ti alloys.

The effects of solution additives and gas-phase modifiers on the molecular environment and conformational space of common heme proteins.

The molecular environment is known to impact the secondary and tertiary structures of biomolecules both in solution and in the gas phase, shifting the equilibrium between different conformational and oligomerization states. However, there is a lack of studies monitoring the impacts of solution additives and gas-phase modifiers on biomolecules characterized using ion mobility techniques. The effect of solution additives and gas-phase modifiers on the molecular environment of two common heme proteins, bovine cytochrome c and equine myoglobin, is investigated as a function of the time after desolvation (e.g., 100-500 ms) using nanoelectrospray ionization coupled to trapped ion mobility spectrometry with detection by time-of-flight mass spectrometry. Organic compounds used as additives/modifiers (methanol, acetonitrile, acetone) were either added to the aqueous protein solution before ionization or added to the ion mobility bath gas by nebulization. Changes in the mobility profiles are observed depending on the starting solution composition (i.e., in aqueous solution at neutral pH or in the presence of organic content: methanol, acetone, or acetonitrile) and the protein. In the presence of gas-phase modifiers (i.e., N2 doped with methanol, acetone, or acetonitrile), a shift in the mobility profiles driven by the gas-modifier mass and size and changes in the relative abundances and number of IMS bands are observed. We attribute the observed changes in the mobility profiles in the presence of gas-phase modifiers to a clustering/declustering mechanism by which organic molecules adsorb to the protein ion surface and lower energetic barriers for interconversion between conformational states, thus redefining the free energy landscape and equilibria between conformers. These structural biology experiments open new avenues for manipulation and interrogation of biomolecules in the gas phase with the potential to emulate a large suite of solution conditions, ultimately including conditions that more accurately reflect a variety of intracellular environments.

Differences in the Effects of Solution Additives on Heat‐ and Refolding‐Induced Aggregation

Although a number of low-molecular-weight additives have been developed to suppress protein aggregation, it is unclear whether these aggregation suppressors affect various aggregation processes in the same manner. In this study, we evaluated the differences in the effect of solution additives on heat- and refolding-induced aggregation in the presence of guanidine (Gdn), arginine (Arg), and spermidine (Spd), and the comparable analysis showed the following differences: (i) Gdn did not suppress thermal aggregation but increased the yield of oxidative refolding. (ii) Spd showed the highest effect for heat-induced aggregation suppression among tested compounds, although it promoted aggregation in oxidative refolding. (iii) Arg was effective for both aggregation processes. Lysozyme solubility assay and thermal unfolding experiment showed that Spd was preferentially excluded from native lysozyme and Arg and Gdn solubilized the model state of intermediates during oxidative refolding. This preference of additives to protein surfaces is the cause of the different effect on aggregation suppression.

A microstructural model for predicting high cycle fatigue life of steels

In this study, a life prediction model for high cycle fatigue was developed by considering the influence of microstructural parameters such as grain size and precipitates. The effect of solute addition on the fatigue crack growth rate in stage I and stage II was considered in the earlier model for pure iron, which reflected only the effect of grain size. As the solute atoms were added, an additional friction stress for the dislocation movement was expected to occur, resulting in the reduction of the driving force for the propagation of small fatigue crack. It was found that the friction stress could be expressed by a similar form of Hall–Petch equation in the high cycle fatigue. High cycle fatigue tests were performed for the steels with the various grain sizes to obtain several constants in the proposed model and to verify the validity of the model. Reasonable agreement was found between the experimental data and the predicted curve.

Evolution of Surface Roughness during Copper Electrodeposition in the Presence of Additives: Comparison of Experiments and Monte Carlo Simulations

The effect of solution additives on surface roughness evolution during copper electrodeposition on flat copper surfaces was investigated by comparing experimental measurements with numerically simulated results. Deposition was carried out on Cu(111) surfaces for 300 s at 10-20 mA/cm2 with solutions of with various combinations of 1.5 mM 500 ppm polyethene glycol MW 3400, and either 2 mM or 2 μM 3-mercapto-1-propane sulfonic acid. Potential transients and surface roughness data were measured and compared with multiscale numerical simulations carried out with a noncontinuum Monte Carlo model of the surface linked to a continuum model of the diffusion layer. Hypotheses for electrodeposition of copper in additive-free solutions as well as those containing one, two, or three additive components were selected from the literature and encoded into a Monte Carlo model. The simulations included up to 32 parameters of which some were available from independent measurements and the remaining were selected to match experimental data. Simulations were carried out on the Condor high-throughput system. Comparison of numerical results with experimental data led to recognition of several areas for improvement. These included (i) recognizing the need for high-throughput experimental methods for obtaining a sufficient quantity of data to establish statistically significant trends, improving numerical procedures to handle pseudoparticle sizes significantly smaller than the 100 nm used here, linking multiscale codes with external scripts to facilitate the use of different modules at one scale without affecting the operation of the module used at another scale, and automating the process for obtaining values for the most sensitive parameters. © 2003 The Electrochemical Society. All rights reserved.

Fe-Zn phase formation in interstitial-free steels hot-dip galvanized at 450°C: Part II 0.20 wt% Al-Zn baths

The effect of solute additions of titanium, titanium and niobium and phosphorus on interstitial-free steels on Fe-Zn phase formation after immersion in a 0.20 wt% Al-Zn bath was studied to determine the morphology and kinetics of the individual Fe-Zn phases formed. These results were contrasted to the previous study using a pure zinc (0.00 wt% Al) bath in Part I. It was found that in the 0.20 wt% Al-Zn bath, an iron-aluminide inhibition layer prevented uniform attack of the steel substrate. Instead, localized Fe-Zn phase growth occurred, termed outbursts, containing a two-phase layer morphology. Delta-phase formed first, followed by gamma-phase. Zeta-phase did not form in the 0.20 wt% Al-Zn bath, in contrast with zeta-phase formation in the pure zinc bath. As in the pure zinc bath, the growth kinetics of the total layer was controlled by the Fe-Zn phase in contact with the liquid zinc during galvanizing. For the 0.20 wt% Al-Zn bath, the Fe-Zn phase in contrast with the liquid zinc was the delta-phase, whereas the zeta-phase was in contact with liquid zinc in the pure zinc bath. The delta-phase followed t1/2 parabolic growth, while the gamma-phase showed essentially no growth after its initial formation. Titanium and titanium + niobium solute additions, which enhance grain-boundary reactivity, resulted in more rapid growth kinetics of the gamma- and delta-phases. Phosphorus additions, which decrease grain-boundary reactivity, generally increased the incubation time and retarded the growth rate of the gamma-phase. These results further confirm the concept that solute grain-boundary reactivity is primarily responsible for Fe-Zn phase growth during galvanizing in a liquid Zn-Al bath in which an iron aluminide inhibition layer forms prior to Fe-Zn phase formation.

The Effect of Additives on the Perovskite-like Phase Formation from Bi-Ti Complex Alkoxide Solutions

Bi-Ti複アルコキシド溶液の部分加水分解の際に添加する触媒種と量が, Bi4Ti3O12 薄膜の結晶相の出現にどのような影響を与えるか調査した。その結果, 0.01mol の水のみを添加した条件でペロブスカイト-類縁相の出現率が高いことが明らかになった。本研究で合成した Bi-Ti 複アルコキシド溶液のように酢酸基を含むアルコキシド溶液の場合は,添加剤の効果が顕著であり,添加する触媒種により複アルコキシドの構造と加水分解および重縮合反応,さらには析出したフィルムのゲル構造が大きく変化したと考えることができる。またこれらの結果から,得られるセラミックス薄膜の結晶相がコントロールできる可能性が示された。

Influence of Solute Additions on Electromigration in Aluminum

AbstractThis study investigates the effect of solute additions on electromigration in Al-based thin film binary alloys. The “cross-strip” technique was used to observe solute electromigration and its influence on Al electromigration. The results of electromigration tests on five alloy additions, Ag, Au, Cu, Pd and Ni, are presented. It is concluded that beneficial solutes have two characteristics. First, they have a large, negative effective valence (Z**). Second, they have sufficient solubility in Al at test temperature to provide a reservoir of mobile atoms. Ag and Au are relatively ineffective because of their low effective valence. Pd and Ni appears to be relatively ineffective because of their low solubility at test temperature. Only Cu satisfies both criteria.

Effect of solute addition on swelling of vanadium after FFTF irradiation

Effects of solute addition on the swelling of vanadium have been investigated by transmission electron microscopy following neutron irradiation in FFTF to 31.5, 31.9 and 34.2 dpa at 410, 520 and 600°C, respectively. Addition of iron drastically enhances the swelling as much as 160% at 600°C, while molybdenum suppresses the swelling to 0.07%. The present results are interpreted in terms of the atomic size effect of the alloying elements; smaller sized solute atoms yield larger swelling.

The effect of radiation-induced segregation on void swelling in electron-irradiated austenitic Fe-Cr-Ni-Ti-P Alloy

It has been reported that the void swelling in austenitic steels at higher temperatures is enhanced by a nickel depletion in matrix . The objective of the present study is to understand the effect of solute addition on void swelling, in association with microchemical changes, in austenitic steels during electron irradiation.Four types of model alloys (Fe-16Cr-17Ni, Fe-16Cr-17Ni-0.25Ti, Fe- 16Cr-17Ni-0.1P, Fe-16Cr-17Ni-0.25Ti-0.IP) and JPCA-2 were used in this study. Irradiation and in-situ observation were carried out with 1.0 MeV electrons utilizing JEM-1000 of HVEM Lab. Kyushu Univ.Fig. 1 shows the irradiation temperature dependence of nickel concentration in matrix after irradiated at 2 dpa. The ternary alloy and alloys containing phosphorus(or titanium) only show a strong nickel depletion in matrix due to nickel segregation to defect sinks. Our previous results about void swelling in these alloys showed that the temperature, where nickel depletion in matrix became prominent, corresponded to that of maxium void swelling. On the other hand, void swelling and the nickel depletion were not detected in Fe-16Cr-17Ni-0.25Ti-0.IP and JPCA-2.

Solid Solubility Effect on Properties of Titanium Diboride

The effect of solute additions on the lattice constants of (Ti,Me)B2 alloys is reported. The data are based on the literature and on additional experimental work. Variation of lattice constants, calculated from crystallochemical principles, agrees satisfactorily with measured values for dilute solid solutions. Increased solute concentration causes positive deviation for (Ti,Cr)B2, (Ti,Zr)B2, and (Ti,Al)B2 because lattice dilation is affected by both the valence of the solute and the size of the metallic radii. It is postulated that lattice anisotropy and elastic strain energy increase in the solid solutions and that they determine the grain‐boundary cohesion in polycrystalline TiB2. Knowledge of the lattice dilation properties of TiB2 solid solutions indicates how the mechanical behavior of diboride ceramics could be improved.

Imaging of Dislocations and SUB–Grain Boundaries in Alumina Through Chromia – Vacancy and Molybdenum Solute Atmospheres

ABSTRACTThe phenomenon of plastic flow in alumina was previously [1 and 2] characterized using sintering models and transmission electron microscopy. Some of the findingsof the work were (a) near equality in the activation energy for volume diffusion and surface area reduction (82 kJ/mol), (b) a higher activation energy (440 kJ/mol) for Coble creep mechanism in the absence of gamma/alpha phase transformation and a lower activation energy (250 kJ/mol) when phase transformation was a part ofthe sintering process and, (c) presence of extended dislocations and deformed electron diffraction spots.In view of these results it was of interest to follow the effect of solute addition on plastic flow [ 3 ]. The solutes were incorporated in alumina through gel synthesis route and formed solid—solution systems of Cr203— A1203 and MoO3 — A12O3 at 1000°C. In the course of sintering there is partiai vaporization of caromiaand reduction of MoO3. The chromiavacancy and Mo metal thus impart an impurity decoration to the lattice. The scanning electron micrographs seem to show that they are segregated along grain boundaries, sub—grain boundaries and dislocations. With increase in temperature the linear vacancy segregations and the scattered vacancy clusters annihilate to form pores. These pores transform to creep cavities that extend from grain boundary to volume. The clustered occurrence of Mo at grain boundaries and its extended spacing in the subgrain boundary is perhaps indicative of a dislocation pipe model for its segregation. On the basis of these modeling and microstructural results a heuristic argument is presented in favor of kinetic equality among self diffusion, dislocation pipe diffusion and dislocation climb, and in favor of the commencement of Coble and Nabarros—Herring creep with severance of these equalities.

The effect of solute additions on void nucleation

In 316 stainless steel and other alloys, nickel and silicon appear to be major determinants of the radiation-induced swelling behavior. In this study it has been shown that the fast-diffusing species concept proposed by Venker and Ehrlich appears to be a viable mechanism for suppression of void nucleation by silicon atoms. While the role of silicon can be ascribed at least partially to the fast-diffusion effect, the role of nickel cannot, and its influence appears to lie in the operation of other physical mechanisms. The enhanced diffusivity of the alloy which results from the addition of silicon leads to a substantial increase in the free energy barrier to void nucleation, particularly at higher temperatures. The fast-diffusion mechanism operates in addition to the interstitial-solute binding effect, and the combined fast-diffusion/interstitial binding model dispenses with the requirement of unrealistically large interstitial-solute binding energies needed for the solute-binding concept to suppress swelling. Solute binding may account for most of the observed silicon segregation behavior while fast-diffusion accounts for the void suppression. The addition of slow-diffusing elements has an opposite but less pronounced effect on void nucleation.

A simplified phenomenological model for non-elastic deformation: Predictions of pure aluminum behavior and incorporation of solute strengthening effects

From a previously-presented phenomenological model for monotonic and cyclic deformation, a simplified set of constitutive equations is derived. Quantitative predictions for pure aluminum are compared with the corresponding experimental data for a variety of test situations, including (1) the effect of temperature and strain level on the strain-rate sensitivity, (2) the effect of applied stress on the amount of primary creep, and (3) response to complex loadings such as abrupt changes in stress. A major addition is made to the equations to incorporate solute strengthening effects; the resulting model can generate fairly realistic predictions of (1) the effect of temperature on the yield strength, (2) the effect of solute additions on strain-rate sensitivity, (3) the effect of work hardening on flow stress and strain-rate sensitivity, (4) the effect of solute additions on steady-state creep behavior and (5) peaks in apparent activation energy.

Kirkendall study of electromigration in thin films

A series of experiments has been designed to measure the effects due to solute addition on electromigration in thin films. These experiments are based on a “cross-stripe” sample geometry and in principle are similar to the Kirkendall study of bulk diffusion couples. An analysis of grain boundary electromigration is presented here to show how one can measure (a) the effect of solute addition on solvent electromigration at grain boundaries, (b) the critical solute concentration required for reducing electromigration damage and (c) the solute effective charge and diffusivity at grain boundaries. Measurements have been made for Cu in Al and for Ag in Au over a limited range of temperatures near 250°C and results are reported. Data obtained for Cu in Al are sufficiently detailed for the self-consistency of our measurements and the validity of the analysis to be examined. The overall agreement is satisfactory.

The effect of solute additions on the steady-state creep behavior of dispersion-strengthened aluminum

The effect of solute additions on the steady-state creep behavior of coarse-grained dispersionstrengthened aluminum alloys was studied. Recrystallized dispersion-strengthened solid solutions were found to have stress and temperature sensitivities quite unlike those observed in single-phase solid solutions having the same composition and grain size. The addition of magnesium or copper to the matrix of a recrystallized dispersion-strengthened aluminum causes a decrease in the steady-state creep rate which is much smaller than that caused by similar amounts of solute in single-phase solid solutions. All alloys exhibited essentially a 4.0 power stress exponent in agreement with the model of Ansell and Weertman. This was observed even in alloys whose matrix shows a much lower stress exponent when tested as a single-phase solid solution. The activation energy for steady-state creep in dispersion-strengthened Al−Mg alloys, as well as the stress dependence, was in agreement with the physical model of dislocation climb over the dispersed particles. For the dispersion-strengthened Al−Cu alloys, the activation energy for steady-state creep suggested that the kinetics of dislocation climb may be related to the mobility of copper'atoms in the matrix. Electron microscopic examination of the dislocation structure present after steady-state creep had been reached suggested that few mobile dislocations are involved in the steady-state creep process at the stress levels employed in this investigation.

The Frequency of Annealing Twins

AbstractThe frequency of occurrence of annealing twins as a function of grain size, and of annealing temperature and time has been studied in copper and in a series of copper-base alloys containing nominally 2 atomic per cent of Ag, Zn, Al, Si, and Sn. It is shown that twinning frequencies, υ, are not independent of grain size as is frequently assumed, and that a maximum value of υ may be expected at some intermediate grain size. Twinning frequencies, furthermore, depend on the time and temperature of heat treatment used to obtain a given grain size. The practice of using twinning-frequency data to categorize alloys according to stacking fault energies is shown to be innacurate unless prior knowledge of the effects of solute additions on the grain-boundary free energy is known. The effect of solute additions on twinning frequency is manifested primarily through a lowering of the grain-boundary free energy, which results in substantially lower values of υ for dilute alloys.

Lattice parameters of magnesium alloys

The effect of solute additions on the lattice parameters of magnesium alloys is reported. Empirical equations are derived from the data which have allowed the calculation of the lattice parameters of ternary solid solutions from binary data. The data are taken both from the literature and from additional experimental work.