Chemical Composition Of Alloy Research Articles

Distribution of Alloying Elements in the Structure of Heat-Resistant Nickel Alloys in Secondary Carbides

The use of x-ray spectroscopy is considered for studying the specific distribution of alloying elements in structural components of heat-resistant nickel alloys, namely, between secondary carbides, since the role of carbides in the formation of the properties of these alloys is complex. Thermodynamic processes of separation of excesses of phases are theoretically modeled using the CALPHAD method in the JMatPro software suite. Also, structures and distributions of chemical elements in carbides are studied as functions of the alloying level using an REM-106I scanning electron microscope. Phase reactions in typical carbides M23C6 and M6C in alloy ZhS6K tend to transform depending on the doping level by the given elements. Mathematical dependences of the infl uence of the alloying level on the carbide separation (dissolution) temperature and of changes in the alloy chemical composition on the contents of elements in the carbides are established. Carbide M6C gradually degenerates as the Cr content increases and disappears at 11 mass%. A topologically close-packed phase is formed in the structure with 3 mass% Mo in the alloy. Carbide M6C approaches the Mo-based monocarbide with 8 mass% Mo. Dependences of the carbide separation (dissolution) temperature on the amount of tungsten (W) in the alloy are calculated. The separation (dissolution) temperature of all carbides in the alloy increases as the W content in the alloy increases. A topologically closepacked phase separates in the alloy at a W concentration of 11 mass% and has negative effects on the properties of the studied system. The obtained dependences are experimentally confi rmed using x-ray spectroscopy on heatresistant Ni-based ZhS6K alloys. The stoichiometric formulas of the carbides are calculated. The theoretical and practical results are compared and found to be in agreement.

Metallurgy of a Ti–Au alloy synthesized by controlled electric resistance fusion

In this study, the first attempt was made to synthesize a Ti–Au alloy by fusing two titanium plates and a thin gold foil between them using the small-scale resistance spot welding procedure. The main goal was to study the possibility of controlling the alloy synthesis process by predefined thermal cycles (metal heating and its cooling rate). The Ti–Au alloy microstructure, chemical and phase compositions, as well as hardness distributions were studied by scanning and transmission electron microscopy, energy dispersive X-ray analysis, and nanoindentation. As a result, a weld nugget with optimal sizes for titanium alloys was formed. The average gold content in the synthesized Ti–Au alloy was about 16 at. % (42 wt %). It was distributed rather evenly throughout the nugget volume in ratios of 10–20 at. % (30–50 wt %). In addition to α-Ti and Au particles, the alloy included the Ti3Au and TiAu2 compounds corresponding to the gold content of 25 and 67 at. %, respectively. These compounds had formed in microvolumes contained high gold concentrations for a period of less than 3 ms. Hardness values were from 6 up to 7 GPa in the regions most enriched in gold, and they were about 4 GPa where the gold content was minimal. Based on the obtained results, some ways were proposed for the possible optimization of this research method.

Effects of thermomechanical treatment on the microstructure, precipitation strengthening, internal friction, and thermal stability of Al–Er-Yb-Sc alloys with good electrical conductivity

Rare-earth elements improve the mechanical properties of aluminum owing to the formation of the L12-structured nanoprecipitates providing the precipitation strengthening effect. The precipitates type, size, and number density depend on the alloy chemical composition and a thermomechanical treatment regime. It is essential to develop the alloys and treatments, providing a combination of the enhanced mechanical strength and a high level of electrical conductivity. This study investigates the influence of thermomechanical treatments on the microstructure, precipitation strengthening, mechanical properties, and electrical conductivity of Al–Er-Yb-Sc alloys with differing Sc content. An as-cast structure of the alloys studied consists of a supersaturated aluminum solid solution and Al3(Er,Yb) phase particles of eutectic origin with the particle thickness of 50–200 nm. A significant strengthening during post-deformation annealing is achieved by precipitation of L12-Al3(Sc,Er,Yb) phase dispersoids of 4–8 nm in size. The mechanical spectroscopy method is successfully used to understand the precipitation kinetics of the studied alloys in comparison with analogous Al-Yb-Y-Sc alloys. This method is highly sensitive to lattice defects parameters, i.e., recrystallization and precipitation kinetics. High-scandium alloys demonstrate an increase of the hardness and tensile strength and insignificant changes in the internal friction background level during post-deformation annealing of cold-worked samples at 300 °C. The yield strength of the Al–Er-Yb-Sc alloys after post-deformation annealing is 142–231 MPa, elongation-to-failure is 3.6–13.5%, and electrical conductivity is 54.8–60.9% IACS, dependent on scandium content and annealing parameters. The studied alloys exhibit high thermal stability of the tensile properties, which remains unchanged during annealing at 300 °C for 100 h.

Selective Formula as A Corrosion Inhibitor to Protect the Surfaces of Antiquities Made of Leather-Composite Brass Alloy

The interactions between the metal and the surroundings are responsible for electrochemical reactions that contribute to corrosion. To mitigate or deter corrosion of exposed metal in a corrosive environment, and corrosion agent must be applied to the metal surface to prevent further oxidation and therefore the presence of corrosion materials. One of the common techniques used by professionals associated in conservation-restoration to preserve metallic cultural heritage is the corrosion inhibitors. The second section of the thesis deals with the conservation and management by using an environmentally friendly corrosion agent of the corrosion of brass composite brass leather parts from the Bulaq Museum, Cairo, Egypt. Microscope Optical and scanning electron Analysis was performed to determine the microstructure of the alloy. Determining the alloy chemical composition of the identified objects using dispersive energy spectroscopy (EDS). Using X-ray diffraction (XRD), corrosion products were established. Finally, the effectiveness of composites between industrial corrosion inhibitors and surfactant materials was identified by the positive effects of (TTA + SLS) on handling. Before and after treatments the brass surfaces were described using SEM, EDS, XRD, FTIR, and XPS.

Control of kinetics of plasma assisted nitriding process of Ni-base alloys by substrate roughness

AbstractThe present study investigated the effect of surface roughness on plasma assisted nitriding (PAN) process kinetics of Ni-base alloys. Two model alloys, namely Ni-10Cr and Ni-14Cr-4Al (wt.%) and commercial Rene 80, were examined. To elucidate the effect of surface roughness on nitriding kinetics, three methods of surface preparation were used, (1) polishing up with 1 μm diamond suspension, (2) grinding up to 220 grit sand-paper, and (3)grit blasting. The samples from each type of material were nitrided under the same conditions and investigated after processing. It was found that increase in roughness results in decreasing nitriding kinetics. The decrease of nitriding kinetics depends on alloy chemical composition, namely more complex chemistry resulted in smaller decrease of kinetics. Moreover, grit-blasting was found to be an improper method for surface preparation for PAN. The responsible mechanism for the effect of surface roughness on PAN kinetics of Ni-base alloys was proposed.

Effect of hardenability on microstructure and property of low alloy abrasion-resistant steel

Low alloy abrasion resistant steel is widely applied in harsh working fields, such as mining, construction and cement production. Hardenability is one of principal factors which affect the service life of abrasion-resistant steel. The goal of this work was to investigate the effect of hardenability on microstructure and mechanical properties throughout thickness of low alloy abrasion resistant steel. Three kinds of 50 mm thickness wear resistant steels with different low alloy chemical composition and the same heat treatment process were produced and compared. Results show the hardness decreases along the thickness direction from surface to the middle and the hardness variations are 16.4%, 2.6% and 3.5% respectively. The strength in the 1/4 layer is larger than that in the 1/2 layer in both horizontal and vertical direction. The strength and impact toughness differences along thickness of the steels with more hardenability promoting elements are smaller, with tempered martensite dominates the whole thickness plate. While the hardened layer of the steel lack of hardenability elements is only about 10 mm and its 1/2 thickness layer is dominated by bainite with relatively poor wear property. Furthermore, the precipitates in 1/2 and 1/4 layers of three steels show remarkable differences.

Effect of surface mechanical attrition treatment on stainless steel corrosion

ABSTRACT Surface mechanical attrition treatment (SMAT) is a unique method for the nanoscale refinement of a surface grain structure without changing the alloy chemical composition. Herein, the effect of SMAT on the corrosion resistance of 316L stainless steel in artificial sea water used as a corrosive medium has been investigated. As a result, a passive film and a nanostructured layer were formed on the SMAT-processed 316L stainless steel surface, which considerably increased its corrosion resistance during short-term testing. However, after a long-term exposure to the corrosive medium, the treated sample exhibited deterioration of its corrosion properties because of the micro-strain build-up and the presence of defects in the surface layer. The findings of this work suggest that SMAT can be potentially used for providing short-term corrosion protection to stainless steel objects immersed in aqueous saline media.

Prediction of the Bilinear Stress-Strain Curve of Aluminum Alloys Using Artificial Intelligence and Big Data

Aluminum alloys are among the most widely used materials in demanding industries such as aerospace, automotive or food packaging and, therefore, it is essential to predict the behavior and properties of each component. Tools based on artificial intelligence can be used to face this complex problem. In this work, a computer-aided tool is developed to predict relevant mechanical properties of aluminum alloys—Young’s modulus, yield stress, ultimate tensile strength and elongation at break. These predictions are based on the alloy chemical composition and tempers, and are employed to estimate the bilinear approximation of the stress-strain curve, very useful as a decision tool that helps in the selection of materials. The system is based on the use of artificial neural networks supported by a big data collection about technological characteristics of thousands of commercial materials. Thus, the volume of data exceeds 5 k entries. Once the relevant data have been retrieved, filtered and organized, an artificial neural network is defined and, after the training, the system is able to make predictions about the material properties with an average confidence greater than 95 % . Finally, the trained network is employed to show how it can be used to support decisions about engineering applications.

Simulation of Hip Joint Implants Using Finite Element Method with Time and Load Variations

This research aimed to analyze the results of a hip joint implant made from Mg alloy using experimental and simulation methods with Finite Element Analysis (FEA). The experimental method’s target was to observe the microstructure, crystallite size, and magnesium alloy chemical composition. The simulation method was designed to analyze the total deformation, maximum principal stress, and maximum shear stress with time and load variations. This research used SEM, XRD, and XRF instruments to obtain the above data whereas FEA simulation used the ANSYS software. The simulation was conducted through walking, jumping, and walking down the stairs activities for 0–4.5 seconds. The SEM results showed that Mg alloy powder had an irregular shape or non-uniform particles with cracks or porous. The XRD results indicated that the crystallite size was 0.516 x 10-4 nm. Then, the XRF results presented that Mg alloy powder had 11% Mg, 61.17% Ca, and 5.73% Zn. FEA results showed that the hip joint implant had a total deformation of 0.38 nm in walking activity, 0.82 nm in jumping activity, and 0.90 nm in walking down the stairs activity. The maximum shear strains were125.98 MPa in walking, 264 MPa in jumping, and 291 MPa in walking down the stairs. The maximum principal stress in walking activity was 192.76 MPa, in jumping was 397.48 MPa, and in walking down the stairs was 438.85 MPa.

Development of the Chromium-Rich High-Speed Steel: As-Cast Microstructure

The present study has been undertaken to replace W by Cr in as-cast HSSs using B as alloying element. For this reason, a special alloying system was suggested. The basic steel containing approximately 12 wt. % of Cr was alloyed with B, V, V and Mo in different proportions. The microstructure of the steels was studied using electron microscopy, X-ray diffraction, and energy dispersive X-ray analysis. It was shown that the matrix structure, as well as the origin and morphology of the carbides or carboborides formed during solidification greatly depended on the alloy chemical composition.

Anomalous effect of Si additions upon the paramagnetic-to-antiferromagnetic transition entropy in fcc high-Mn steels

Fe–Mn based alloys with more 12% at. of Mn are usually called High-Mn steels. Several technological properties of High-Mn steels are explained by the presence of the fcc-hcp martensitic transformation. This transition is strongly affected by the para-to-antiferromagnetic ordering transition present in the fcc structure. The magnetic ordering temperature depends on the alloy chemical composition, and strongly stabilizes the fcc austenitic phase, leading to a decrease of the structural transformation temperatures. In several cases, this effect is strong enough to inhibit the martensitic transformation. In the present study, the effect on the magnetic transition of adding Si to high-Mn Fe–Mn alloys is analyzed. Calorimetric measurements are performed in order to obtain the entropy change associated to the magnetic ordering transition. The results are discussed in the light of the available information in the literature. Striking effects are reported, which indicate that Si addition strongly affects the driving force of the martensitic transition.

A Review of Development of Zirconium Alloys as a Fuel Cladding Material and its Oxidation Behavior at High-Temperature Steam

Currently, Zr-alloys are widely used in nuclear power reactors for fuel cladding and structural components. Many types of zr-based alloys were developed to overcome the challenges encountered in the progress of nuclear reactors (high-burnup and high-duty). Oxygen diffused into the cladding, hydrogen absorbed in the cladding (breakaway oxidation and ruptured balloons) and rapid oxidation rate are results of chemical interaction of cladding material with steam at high temperature. Zirconium alloys seem to be the most suitable for use in fuel cladding, if they can overcome the rapid oxidation at temperature higher than 1200 °C. Previous studies on the oxidation behavior for some Zr-alloys nuclear fuel cladding tubes in steam and steam–air atmospheres at high temperatures are reviewed. The oxidation behavior of zirconium-alloys is strongly affected by the chemical composition of alloys and its surface conditions.

Study on the Forecasting of the Hot Corrosion Resistance of Typical Superalloys for Aeroengines

The high-temperature components of aeroengines are in contact with gas flow for a long time, making them susceptible to hot corrosion, which can affect the reliability and lifespan of aeroengines. In this study, five types of superalloys commonly used in the high-temperature components of Aeroengines are selected for gas-based hot corrosion tests, and the corrosion rates are calculated using the weight loss method. Gradient Boosting Regression Tree (GBRT) machine learning algorithm is utilized to establish a corrosion rate forecasting model. The evaluation results show the predictability of this method. The effect of input parameters, including main alloy chemical composition and corrosion time, on the corrosion rate was discussed using GBRT and critical factors are obtained. These results provide a reference for the protection of aeroengines from hot corrosion.

Insights into high-temperature oxidation of Fe-Mn-Si-Cr-Ni shape memory stainless steels and its relationship to alloy chemical composition

The relationship between alloy chemical composition and oxidation behavior of austenitic Fe-Mn-Si-Cr-Ni shape memory stainless steels (SMSSs) during exposure at 800 °C in air was investigated. Although high Si and Cr additions are beneficial for both the shape memory effect and oxidation resistance, the increase of these ferrite stabilizer elements in Fe-Mn-Si-Cr-Ni SMSSs makes the oxidation-induced ferrite stable at the early stages of the oxidation exposure, which in turn allows a faster diffusion of Mn, controlling the kinetics of oxidation. Our results suggested that the austenite stability should be maintained during the oxidation process for higher performance of these materials.

Fabrication and micro-structural evaluation of ODS austenitic stainless steels through mechanical alloying

Abstract This work is aimed at developing an oxide dispersion strengthened (ODS) austenitic stainless steels by Mechanical Alloying (MA) process. Two different alloys such as Alloy A and Alloy B were prepared from pure elemental powders with the addition of Y2O3 (Yttrium oxide). The chemical composition of Alloy A and Alloy B was 17Cr-8Ni-8Mn and 17Cr-8Ni-8Mn-0.5Ti-0.3Y2O3. Structural evaluation was studied by using XRD and SEM. The crystallite size of Alloy A and Alloy B powders after 30 h of ball milling were 250 nm and 14 nm. It was found that the Alloy B showed higher density than Alloy A.

Time-dependent corrosion properties of Sr-modified AlSi9 alloy analyzed by electrochemical techniques

The relation between time-dependent corrosion behaviors and microstructural characteristics of Sr modified and unmodified AlSi9 alloy was studied. The melted alloys were cast into the permanent mold at 700 °C casting temperature. The Effect of holding time in the furnace on chemical compositions of alloys was determined. Sr content of the modified alloys was 200 ± 5 ppm after 4 h and 50 ± 2 ppm after 17 h holding time. Microstructural properties were analyzed after casting. The corrosion behavior of AlSi9 depending on Sr content was investigated by means of electrochemical impedance spectroscopy technique and potentiodynamic polarization plots in 3.5 wt% NaCl solution at 25 °C. The effect of immersion time was examined at 1, 24, 72 and 120 h. The results indicated that high Sr content in AlSi9 alloy contributes to the formation of a finer eutectic phase and more stable corrosion behavior during immersion time.

Comparison of the Phase Stability and Corrosion Resistance of the Ni-Based Alloys C-4 and C-276

A one-to-one correspondence is developed between the phase stability and corrosion resistance of the commercial (Ni-Cr-Mo)-based alloys C-276 and C-4. Alloy C-4 is shown to outperform alloy C-276 in acidic oxidizing media and approaches its resistance in acidic reducing media. Both alloys are found to have similar resistance to chloride-induced stress corrosion cracking in the annealed condition with short-range order. The aqueous corrosion resistance of both alloys is found to be improved by long-range order; however, they become highly susceptible to chloride-induced stress corrosion cracking. Alloy C-4 is distinguished by being stable toward precipitation of detrimental intermetallic compounds. However, alloy C-276 is shown to be prone to precipitation of mu phase which degrades its resistance to aqueous corrosion and chloride-induced stress corrosion cracking. It is concluded that the chemical composition of alloy C-4 is tailored to make it more versatile than alloy C-276 in acidic oxidizing media and the results are found to be consistent with the concept of atomic percent factor of each alloy.

Influence of chemical composition on the conductivity and on some mechanical properties of Mg-doped Cu-Si alloy

This study discussed the influence of chemical composition on the conductivity and on some mechanical properties of Mg-doped Cu-Si alloy. The structural changes accompanying variations of the alloy chemical composition was investigated using Carl ZEISS Scanning Electron Microscope (SEM) (EVO/NA10) and Energy Dispersive Spectroscopy (EDS). The study also discussed the implication of structural changes on the electromechanical behavior. The results obtained were analyzed statistically using one-factor response surface method (RSM-Design Expert software) to evaluate the level of significance of magnesium addition on Cu-3Si-Mg ternary alloy properties. The SEM results revealed fine grains in the Mg-doped Cu-3Si alloy. The study recorded improvement of properties: average ductility of 25.1%, UTS of 285 MPa; hardness of 318 BHN and average electrical conductivity of 53.9% IACS. The statistical analysis indicated that magnesium significantly improved all the tested properties haven recorded P-values < 0.05. The result of optimization revealed Cu-3Si-0.837 Mg as the optimal composition.

Design and examination of the new biosoluble casting alloy of the system Mg–Zr–Nd for osteosynthesis

We have performed a comparative analysis of existing materials for the fabrication of implants and report their physical-mechanical properties; their advantages and disadvantages have been defined. It is shown that magnesium alloys are among the most promising biosoluble materials. They are bioinert and biocompatible, but their use in osteosynthesis is limited mainly by their inadequate mechanical properties due to the high rate of biodegradation, which requires improving them by changing the chemical composition of the alloy. In order to develop a new magnesium-based biosoluble alloy, we have selected the most suitable doping systems in accordance with the established criteria. Employing the methods of experiment design, we studied the separate and joint influence of zirconium, neodymium and zinc on structure formation and mechanical properties of magnesium alloy. Mathematical models have been constructed that describe the influence of the examined alloying elements on the mechanical properties of the metal. Using the regression equations derived, we have carried out the optimization of the chemical composition of magnesium alloy. The industrial and pre-clinical tests of implants made from the designed biosoluble alloy have been performed. Experiments on animals confirmed the absence of toxic effect from the products of degradation of the devised magnesium alloy on a living organism. Studying the influence of the designed alloy on reparative osteogenesis during experiment on rabbits has shown the positive dynamics of bone tissue regeneration without noticeable changes in its structure, which ensures reliable merging of elements in bones at osteosynthesis. It was established that the implants made from the designed alloy possess the necessary level of mechanical properties that match the mechanical properties of bone tissue. At the same time, they are non-toxic and provides a secure bone tissue healing until the complete fracture consolidation. Positive results of the experiments conducted allow us to suggest a favorable prognosis on the possibility of using implants made from the devised biosoluble alloy of the system Mg–Zr–Nd in humans

Recasting as a booster of Ag-Pd alloy cytotoxicity: Induction of cell senescence prior to mass cell death

The biological quality and chemical composition of alloys used in dental practice change during heat treatment. Often the residues of the previous cast are not disposed of but are reused and recycled until consumed. Thus, manufactured dental restorations have modified biological quality and chemical composition, and compromised biocompatibility. The aim of this study was to investigate the influence of repeated casting on the cytotoxicity of the silver-palladium (Ag-Pd) alloy. Our results showed that repeated casting of the Ag-Pd dental alloy affected its biocompatibility by promoting toxicity against transformed fibroblasts in a contact-independent manner. A strong decrease in cell proliferation, induction of senescence and massive cell death were observed in cultures exposed only to a medium previously incubated with dental alloy samples. The obtained data indicated that toxicity mediated by the accumulation of the Ag, Pd, Cu and Zn cations released from the Ag-Pd material was enhanced by recasting. The induction of cell senescence and subsequent apoptotic and necrotic death were accompanied by amplified intracellular production of reactive oxygen and nitrogen species, suggesting their involvement in the cell destruction process. Therefore, compromised biocompatibility after recasting with the Ag-Pd alloy can be the cause of serious local cell destruction, as observed in clinical practice.