Effect Of Microadditions Research Articles

Studying the Effect of Microadditives on the Structural Phase State of Al-Ti Based Alloys

Studying the Effect of Microadditives on the Structural Phase State of Al-Ti Based Alloys

Effects of microadditions on glass transition and hardness of Cu-based bulk metallic glasses

In this paper, glass-forming ability, viscosity, fragility and microhardness of three Cu-based bulk metallic glasses are evaluated by differential scanning calorimetry, thermomechanical analysis and hardness testing. The results suggest that Y element can effectively affect the packing state and properties of Cu-based bulk metallic glasses. The variation of glass-forming ability, viscosity, fragility index and hardness indicates that alloying with low quantity of additions can remarkably change the characteristic temperatures during glass transition stage but cannot cause an apparent modification in the solidification/melting stage.

Effect of Microadding Amine Surfactant on Erosion-Corrosion Wear of Structural Steel in NPP

Corrosion processes, specifically, erosion-corrosion, are one of the causes of damage occurring in NPP equipment during operation. Measures are taken to prevent erosion-corrosion wear of thermal-power equipment and pipelines. One such measure is the development and adoption of water chemistry regimes that are capable of forming a protective fi lm on a metal surface. Octadecylamine is one such reagent. The results of laboratory tests and industrial experiments studying the effect of octadecylamine on the development of erosion-corrosion wear of NPP equipment are presented. The octadecylamine-hydrazine water chemistry regime at octadecylamine concentration 0.5 mg/dm3 reduces the rate of erosion-corrosion wear by about 15-fold. The positive effect of micro-additions of octadecylamine is confirmed by direct erosion-corrosion studies performed at the Kola NPP.

Study of modified gypsum binder

Nowadays the addition of small amounts of chemical additives allows developing new types of binding materials. The effect of microadditives on the performance of β-hemihydrate gypsum has been studied. 1% content of complex additive contributes to enhancement of compressive strength and water resistance in modified samples as compared to reference one. These studies showed that additives accelerate the rate of hydration and lead to the formation of a dense and well-compacted texture of crystals, thereby imparting, to gypsum matrix, higher strength and better water resistance than the reference materials.

Effect of Microadditives on Center Segregation and Mechanical Properties of High-Strength Low-Alloy Steels

One of the main tasks of steelmaking is to obtain the necessary thermodynamic conditions that ensure fine and homogeneous solidified microstructure. The relatively economical solution is to feed microadditives into liquid steel. The metallurgical considerations and techniques on the feeding of microadditives are described in the present work. The effect of small addition of reactive fine particles and ultra-high melting point powders on the control of non-metallic inclusions, slab center segregation, and mechanical properties, especially the Z-direction properties, was investigated. The results showed that the microadditives had composite effects on microalloying and modification of inclusions. The segregation of elements in the slab center of high strength steels was remarkably reduced. The mechanical property along the Z-direction of steel plates was greatly improved.

Effect of Microalloying Elements on the Structure and Phase Stability and Properties of Heat-Resistant Deformable Alloy (with Long Operating Times)

Results are presented for a study of the effect of microadditions of rare-earth and rare metals on the structure and phase stability and mechanical properties of a new high-temperature nickel-base alloy for turbine disks, including long test bases.

Effect of microadditions of magnesium and zinc in aluminum upon heating of cold-rolled sheets

Methods of structural investigations, measurements of hardness, temperature, time, and amplitude dependences of internal friction have been used to study processes of polygonization and recrystallization in Al-0.3 at % Mg and Al-0.3 at % Zn alloys. It has been established that the magnesium atoms more efficiently pin dislocations in the aluminum-based alloys as compared to zinc atoms. Therefore, in the alloy with zinc the process of polygonization occurs more intensely and the processes of softening upon recrystallization occur more slowly than those in the alloy with magnesium.

Alkylation of 2,6-di-tert-butylphenol with methyl acrylate catalyzed by potassium 2,6-di-tert-butylphenoxide

The kinetics of catalytic alkylation of 2,6-di-tert-butylphenol (ArOH) with methyl acrylate (MA) in the presence of potassium 2,6-di-tert-butylphenoxide (ArOK) depends on the method for the preparation of ArOK. The reaction of ArOH with KOH at temperatures > 180 °C affords monomeric ArOK, whose properties differ from those in the case of potassium 2,6-di-tert-butylphenoxide synthesized by the earlier methods. The regularities of ArOH alkylation depend on the ArOK concentration, the ArOH: MA ratio, and the effect of microadditives of polar solvents.

Effect of micro-additions of barium on the quality of industrial pipeline welded joints

The effect of barium on the desphosphorization of weld metal of cold-resistant steels is studied. The optimum concentration of barium metal in the electrode coating and phosphorus in the weld metal is established, and this makes it possible to provide a high strain capacity and crack resistance for welded joint metal made by electrodes with the basic form of a coating.

Effects of micro-additions on structures and properties of rapidly solidified Sn-10% Sb alloy

Structure, electrical resistivity, hardness, internal friction and elastic modulus of Sn-10% Sb and Sn89Sb10M1 (M1 = Ag, Cu, Zn and Pb) alloys have been investigated. No obvious change on the electrical resistivity value was found at 293 °K of a Sn-10% Sb alloy by adding Zn and Cu, but extreme changes occurred after adding Ag and Pb. The elastic modulus, internal friction, hardness and thermal diffusivity values are greatly affected by adding the micro-additions to a Sn-10% Sb rapidly solidified alloy. It is also interesting to note that Ledbetter's theoretical values of μ/E are in good agreement with the experimental results. The rapidly solidified alloys Sn90Sb10 and Sn89Sb10Ag1 have good properties as toxic-free lead solder alloys for high-temperature applications and good mechanical properties such as under the hood in the automobile and avionics systems. Also, the rapidly solidified alloys Sn89Sb10Zn1, Sn89Sb10Cu1 and Sn89Sb10Pb1 have good properties as bearing materials.

Modifying Effect of Microadditives in Silicate and Oxide Ceramic Materials

The results of studying the modifying effect of small additives on the synthesis, sintering structure, and properties of crystalline phases of ceramic materials in the MgO – Al2O3 – SiO2 system and other oxide systems are summarized. The structural-energy criteria for evaluation and prediction of the effect of additives are proposed. Examples of practical use of the preliminary prediction of the modifying effect of additives in silicate and oxide systems in the production of ceramics and ceramic pigments are given.

Effect of beryllium on age hardening, defect structure, and S′ formation in Al–2·5Cu–1·2Mg alloy

AbstractThe effect of micro additions of Be on the aging behaviour, defect structure, and S′ phase formation in Al–2·5Cu–1·2Mg alloy is investigated. It is shown that the addition of 0·15%Be significantly increases the peak hardness and overall precipitation rate for the alloy. An analysis of the kinetic data shows that S′ precipitation obeys the Avrami equation, and that the Be addition does not affect the growth dependent parameter or activation energy, but significantly increases the nuclei density dependent parameter, which is consistent with the higher density of S precipitates in the microstructures of the alloy containing Be. Analysis using transmission electron microscopy shows that Be reduces the dislocation loop density during the early stages of aging, which is attributed to the high Be–vacancy binding energy, and promotes formation of dislocation helices. The enhanced nucleation of S′, notwithstanding the lower density of dislocation loops, which stimulate S′ nucleation, suggests the operation...

Effect of microadditions on the structure and properties of powder carbon steel

1. Additions of alkali metals accelerate the diffusion of carbon in iron, particularly at low sintering temperatures, increase the carbon concentration of the steel, improve the strength properties at all temperatures studied, and produce a more uniform and stable structure. 2. Increasing the amount of alkali metal produces some increase in strength if sodium or potassium are added, but no change if lithium is added. Increase in the diffusional mobility of carbon with increase in the amount of alkali metal added is not observed.

Effect of beryllium and calcium on aging behaviour of Al–0·75Mg–0·5Si alloy

AbstractThe effect of microadditions of Be and Ca on the aging behaviour of Al–0·75Mg–0·5Si alloy is investigated. It is shown that the addition of 0·1%Be significantly increases the hardening rate and the maximum hardness level attainable when the alloy is aged at various temperatures from room temperature to 300°C, while the addition of 0·2%Ca decreases both the hardening rate and the maximum hardness level attainable. Optical and scanning electron microscopical observations show a significantly higher precipitate density for the Be containing alloy and a slightly lower precipitate density for the Ca containing alloy when compared with the base Al–Mg–Si alloy. The results are consistent with an earlier kinetic study that indicated a Be enhanced nucleation rate for precipitation in the same alloy.MST/936

Effect of micro-additions of cerium and boron on the susceptibility of the weld zone of welded joints in lowalloy steels to cracking during tempering

Effect of micro-additions of cerium and boron on the susceptibility of the weld zone of welded joints in lowalloy steels to cracking during tempering

Complex microalloying of low-pearlite steels subjected to controlled rolling

1. The effect of microadditives of vanadium, niobium, and titanium during the individual and complex alloying of low-pearlite steels subjected to controlled rolling is governed by their capacity to form carbides, carbonitrides, or nitrides during thermochemical treatment. These particles contribute to an increase in the strength and resistance to brittle failure either directly, being present in the ferrite in the form of a disperse hardening phase, or by participating in the formation of the steel's structure through different mechansims during thermomechanical treatment (slowing of austenite-grain growth during heating, an increase in the temperature interval of the γ→α-transformation, a reduction in the ferrite-grain size due to the effect of nucleus-formation and slowing of recrystallization of the hot-deformed austenite, intensification of the deformation texture, and refining of the solid solution). 2. The individual effect of vanadium, niobium, titanium, and aluminum microaddicives on the structure and properties of low-pearlite steels depends on their quantity, solubility in the steel matrix, affinity for nitrogen and carbon, and the temperature interval of segregation during hot plastic deformation and cooling after controlled rolling. For complex microalloying, their effect may be additive, or weakened (or even suppressed) by the presence of another, more active element. 3. Heating of thermomechanically hardened steel to normalization temperatures leads to coagulation of disperse particles of the carbonitride phases, their incomplete solution in the austenite, and to a weakening of the effect on the strength of the steel. The effect of high temperature-mechanical treatment (a disperse polygonized ferrite structure), which is obtained as a result of controlled rolling, and, consequently, the positive effect of the elements under consideration on the properties of the steel are eliminated at the same time. 4. The positive effect of vanadium, niobium, and titanium additives can be realized most fully in low-pearlite steels (≤0.12% C), subjected to controlling rolling.

Effects of Microadditions of Cerium on Annealing Embrittlement in FeBSi Glasses

AbstractMicroadditions of cerium retard annealing embrittlement in some but not all metallic glass compositions in the FeBSi system. Effects on embrittlement of doping with both cerium and oxygen have been determined for a series of compositions, FexB13 Si87-x. For X > 80, cerium retards annealing embrittlement and oxygen promotes it, suggesting that the beneficial effect of cerium additions results from gettering of impurities. The results indicate that for those compositions in the FeBSi system with the highest values of the saturation magnetization, Ms, microadditions of cerium can prevent annealing embrittlement until the onset of crystallization.

Austenite grain coarsening in low–carbon manganese steels containing niobium and aluminium

AbstractThe effect of microadditions of niobium, aluminium, and a combination of the two on the austenite grain coarsening behaviour of 0·08C–0·25Si–1·5Mn steels whose nitrogen content was varied/from 0·002 to 0·02 wt-% has been studied. Modified methods of surface oxidation and thermal grooving were used in order to determine the precise prior austenite grain size in these steels with low interstitial elements. The optimum concentration of niobium which could be effectively used for restraining austenite grain growth when steels are austenitized at high temperatures has been determined. It is also demonstrated that steels containing. NbC or NbN particles exhibit similar austenite grain coarsening behaviour. Increasing the nitrogen content from 0·002 to 0·02 wt-% to give nitrogen–rich Nb(CN) particles does not help restrain austenite grain growth. However, when nitrogen was added to steels containing aluminium or aluminium and niobium, significant improvement in grain restraining behaviour was observed.MS...

Improvement in the heat resistance of conductor copper alloyed with zirconium and magnesium

Using conductor materials suitable for operating at elevated temperatures is an increasingly important problem. One of the main conductor materials is copper, and it is possible to increase the strength properties of copper without a marked reduction in ductility by work hardening it with small degrees of deformation, however it is practically impossible to retain these properties at elevated temperatures since pure copper has a low recrystallization temperature which leads to its loss of strength. By increasing the recrystallization temperature for copper it is possible to extend the temperature range for operating conductors in the direction of higher temperatures. Since there is little information about the combined effect of microadditions of zirconium and magnesium on the recrystallization of copper with a varying degree of work hardening, the goal of this study was to determine the effect of microalloying zirconium and magnesium on the temperature range of loss of strength in copper.

Effect of microadditions of zinc stearate and calcium stearate on the rheological properties of polypropylene

Effect of microadditions of zinc stearate and calcium stearate on the rheological properties of polypropylene