Addition Of Alloying Elements Research Articles

Effect of intercritical heat treatment on microstructure, nano-size precipitation and mechanical properties of Fe–Ni–Cu–Al low carbon steel

In recent years, the co-precipitation of nanoscale Cu and Ni–Al particles in Fe–Ni–Cu–Al low-carbon steel provide an extremely high strengthening increment while minimizing the addition of carbon and alloy elements, however, the toughness and plasticity dramatically decreased. This research focuses on the improvement of toughness and plasticity utilizing an intercritical (Quenching-Lamellarization-Aging (QLA)-type) heat treatment for Fe–Ni–Cu–Al steel. The microstructure and nanoparticles precipitation of Fe–Ni–Cu–Al steel were characterized by TEM, HRTEM and phase analysis after a QLA treatment. The results indicate that the multi-phase microstructure consisting of maraging martensite, intercritical ferrite and austenite reversion were obtained by QLA treatment. With decreasing intercritical quenching temperature between 820 °C and 660 °C, −80 °C V-type impact energy and plasticity of Fe–Ni–Cu–Al steel was obviously improved due to the formation of intercritical ferrite and austenite reversion. Meanwhile, the coarsening of Ni3Al particles were markedly accelerated because of Ni segregation in matrix and abundant Fe atoms for the substitution of Al atoms within Ni3Al particles. The strengthening mechanisms of Ni3Al particles in Fe–Ni–Cu–Al steel was mainly Orowan bypassing strengthening after QLA treatment, and the corresponding strengthening increment was calculated as 89% (214 MPa) at the intercritical quenching temperature of 720 °C, which was 17% (259 MPa) lower than the value of order strengthening obtained by 820 °C primary quenching. The combination of multi-phase microstructure and co-precipitation strengthening contributed to excellent mechanical properties (yield strength>1050 MPa at 20 °C, the elongation>13%, a Charpy impact toughness of >80 J at −80 °C) during the intercritical quenching temperature of 720 °C–780 °C.

Redistribution of substitutional alloying elements between α-Fe matrix and cementite after long-term tempering in a low alloying steel

ABSTRACT The partitioning behaviour of non-carbide forming elements (Si, Cu and Ni) and carbide forming elements (Mn and Mo) between α-Fe matrix and cementite (θ) after long-term tempering a quenched reactor pressure vessel (RPV) model steel has been studied by atom probe tomography (APT). It has demonstrated that a non-carbide forming element enriched layer near the interface of α/θ in the α-Fe matrix side is a common feature for tempered steels containing non-carbide forming element, which is widely accepted as the mechanism by which substitutional elements retard the coarsening of cementite. In addition, a carbide forming element enriched layer near the interface of α/θ in the cementite side, Si, Cu and Ni enriched clusters formed in the cementite and Mo2C carbide formed beside cementite were observed, and all this is taken as valuable mechanisms by which addition of substitutional alloying elements can increase tempering resistance of alloying steels.

Effect of Zr, Ti, Ta and Mo addition on high-temperature oxidation and hot corrosion behavior of NiAlY alloys

NiAlY alloys with the addition of Zr, Ti, Ta and Mo were prepared by arc melting. The oxidation and NaCl-induced hot corrosion behavior of the alloys were investigated at 650 ℃, with the focus on the effect of element-doping and phase. With the addition of Ti, Ta and Mo, the oxidation resistance of the tested alloys was effectively enhanced compared to the undoped NiAlY alloy. However, the NiZrAlY alloy showed very poor oxidation resistance. Under the NaCl-induced hot corrosion test, the NiTaAlY and NiMoAlY alloys exhibited an improved hot corrosion resistance, while the NiZrAlY and NiTiAlY alloys showed very poor hot corrosion resistance. Moreover, the NiAl and Ni 5 Y phases exhibited different behavior during the oxidation and NaCl-induced hot corrosion tests. • A new type NiXAlY system doped with different alloying elements was designed in this work. • The oxidation and hot corrosion behaviors of NiAlY alloys with different alloying elements addition such as Zr, Ti, Ta and Mo were investigated at 650 ℃. The effects of different alloying elements on oxidation and hot corrosion resistance were investigated. • Y displayed a negative effect in both oxidation and hot corrosion resistance. The degradation mechanisms of Y-rich areas in the oxidation and hot corrosion tests were different.

Effect of alloying with Ni, Cr and Al on the atmospheric and electrochemical corrosion resistance of ferritic ductile cast irons

The corrosion control of ductile cast irons becomes a technological challenge when supplying castings to customers due to the high reactivity of this alloy in contact with air. An interesting alternative to the protective systems such as coatings or corrosion inhibitors included in packaging processes is the chemical modification of the cast alloys by means of alloying elements addition which are able to improve the corrosion resistance of ductile cast irons. Ni, Cr and Al added to the cast alloys significantly affect their structure and properties, among them their corrosion response, when exposed to air. It has been observed that Ni and Al improve the corrosion behaviour while Cr additionally promoted pearlite and carbides formation. The results from the corrosion tests performed on ductile cast iron alloys which contain these three elements are discussed in the present work.

Effect of novel grain refiner and Ni alloying additions on microstructure and mechanical properties of Al-Si9.8-Cu3.4 HPDC castings – optimization using Multi Criteria Decision making approach

Abstract Studies dealing with process improvement of aluminum alloys and their grain structure refinement are the current area of interest in casting companies and foundries, the aim being to enhance the properties of the base metal. In this study, the microstructural and mechanical properties of commercial Al-Si9.8-Cu3.4 alloy die castings influenced by different additions of Al-3.5FeNb-1.5C master alloy (viz. 0 wt.%, 0.1 wt.%, and 1.0 wt.%) as a new grain refiner and Al-6Ni master alloy (viz. 0 wt.%, 0.5 wt.%, and 5.0 wt.%) as an alloying element have been investigated. A multi-criteria decision-making approach for the improvement of the die casting process was performed using grey relational analysis (GRA) and TOPSIS analytical techniques. It was observed that the primary aluminum α-grains were significantly refined, particularly at the lower addition level 0.1 wt.% of Al-3.5FeNb-1.5C, and conversely, poor grain refining efficiency was observed at a higher addition level 1.0 wt.% of Al-3.5FeNb-1.5C. Due to the refinement by Al-3.5FeNb-1.5C grain refiner and the effect of Ni alloying element additions, the ultimate tensile strength (UTS) and hardness (Brinell and micro) of the Al-Si9.8-Cu3.4 alloy are improved, particularly at 0.1 wt.% of Al-3.5FeNb-1.5C and 0.5 wt.% of Al-6Ni master alloys. Quantitatively, UTS, Brinell hardness, and microhardness values have been increased by 12.3%, 7.0%, and 20%, respectively.

Electrochemical Corrosion Study in H<sub>2</sub>SO<sub>4</sub> of NiAl with Cu Additions, Microstructure and Micro-Hardness at Room Temperature

For many years, intermetallic materials promise applications in a wide variety of technology areas. NiAl intermetallic compound is material that exhibits important characteristics such as high corrosion resistance and low density besides its ability to retain strength and stiffness at elevated temperatures. However NiAl intermetallic is too hard, brittle and exhibits very low ductility at room temperature being the reason because this material is not yet available for structural applications. In order to increase the ductility of the NiAl intermetallic compound, the addition of a third alloying element has been proved, nevertheless it is important to determine if such additions decrease or increase the hardness and the corrosion resistance of the alloy. So, the present investigation reports the corrosion performance of the NiAl intermetallic compound modified with Cu, emphasizing the EIS analysis and the relation between physical parameters and the modelling equations used in the Equivalent Electric Circuit. It was found that the addition of Cu promotes the formation of the γ’-Ni3Al phase in Cu contents greater than 15 at. %, in addition to a decrease in micro hardness and an increment in the Icorr values. In this way, the electrochemical characterization evidenced a high corrosion resistance of these intermetallic alloys.

Effect of Alloying Elements Addition on the Phase Structure and Mechanical Properties of Feconicr High-Entropy Alloy

Effect of Alloying Elements Addition on the Phase Structure and Mechanical Properties of Feconicr High-Entropy Alloy

A Critical Review on the Properties of Intermetallic Compounds and Their Application in the Modern Manufacturing

AbstractAdvancement in modern manufacturing processes is allowing researchers to develop new alloy configurations for different applications to reduce weight and increase efficiency. Many alloy combinations are produced that randomly generate different phases of intermetallic compounds (IMCs) in the structure during manufacturing which show unique mechanical and chemical properties. But, the fundamental knowledge of different IMCs is scattered across the material research domain. Thus, in this review, the crystal structures of IMCs are thoroughly discussed which are having structural and functional applications. Furthermore, the issues associated with the dissimilar Fe‐Al, Fe‐Ni, and Ni‐Al systems via modern manufacturing processes such as arc additive manufacturing have been discussed. Moreover, detailed knowledge of ferro‐nickel, nickel‐aluminides, and ferro‐aluminides formed at the interface during the dissimilar deposition in modern manufacturing is provided. Currently, a few transition metal IMCs and some Heusler alloys, are the most promising and are used in applications. The addition of a third alloying element provides the broadening effect on the phase domain of a specific IMC. Furthermore, it has been observed that modern manufacturing processes such as additive manufacturing and others are new and advanced manufacturing technologies used for dissimilar metal deposition, which can control the IMCs in a more favorable direction.

Effects of La addition on the microstructure and mechanical properties of CoCrNi medium entropy alloy

Ternary CoCrNi medium entropy alloy (MEA) with a face-centered cubic (FCC) structure has been proven to possess superior mechanical properties in many studies. Alloying element addition is a common method to strengthen the alloys; however, the effects of rare earth element addition have rarely been discussed. In this study, different amounts of La were added in CoCrNi MEAs to investigate the microstructure and mechanical properties. (CoCrNi)100-xLax (x = 0, 0.1, 0.2, 0.3 and 0.5) MEAs were fabricated using arc-melting, followed by homogenization, hot rolling and recrystallization. While the structures of La-0, La-0.1 and La-0.2 were FCC solid solutions, LaNi5 precipitates of hexagonal crystal structure formed in the FCC matrix for La-0.3 and La-0.5. The presence of La in FCC matrix not only enhanced the lattice distortion because the atomic radius of La was larger than the other elements in the alloys, but also refined the grain size of the matrix. However, in the presence of LaNi5 precipitates, the La content was reduced in the matrix and the extents of both lattice distortion and grain refinement diminished which, in turn, resulted in the decreased hardness and tensile strength in La-0.3 and La-0.5. The optimum mechanical properties were obtained with small amounts of La addition in La-0.2 because of both solid solution strengthening and grain refinement strengthening.

Influence of Minor Alloying Element Additions on the Crack Susceptibility of a Nickel Based Superalloy Manufactured by LPBF

Inconel 738LC (IN738LC) is a nickel-based superalloy specially used in the hot section components of turbine engines. One of its main drawbacks relies on the cracking susceptibility when it is manufactured by laser powder bed fusion (LPBF). This paper analyzes the influence of minor alloying element concentration on cracking tendency of IN738LC superalloy manufactured by LPBF. For that objective, samples were manufactured using two powders, which presented different minor alloying elements concentration (Si, Zr and B). It was shown that the samples crack tendency was very different depending on the powder used for their manufacturing. In fact, the measured crack density value was 2.73 mm/mm2 for the samples manufactured with the powder with higher minor alloying elements concentration, while 0.25 mm/mm2 for the others. Additionally, a special emphasis has been put on elemental composition characterization in cracked grain boundaries in order to quantify possible Si or Zr enrichment. It has been also studied the differences of solidification ranges and grain structures between both samples as a consequence of different minor alloying elements concentration in order to analyze their effect on crack susceptibility. In this sense, Scheil-Gulliver simulation results have shown that samples with higher Si and Zr contents presented higher solidification range temperature. This fact, as well as an increase of the presence of high angle grain boundaries (HAGB), leaded to an increment in the crack formation during solidification. Therefore, in this research work, an understanding of the factors affecting crack phenomenon in the LPBF manufactured IN738LC was accomplished.

Effect of Mg, La and Ca addition order on inclusions and microstructure of Ti-bearing C–Mn steel

ABSTRACT The influence of addition sequence of Mg, La and Ca on the characteristics of inclusions and the formation of acicular ferrite (AF) were investigated. Results show that inclusions mainly consisted of La–Ca–Mg–Al–Ti–O+MnS in the steel. There was no change to types of inclusions while the layered structure of inclusions was different under different alloy elements addition sequence. The number density of inclusions was the largest in case of Mg was added first, while the average size of inclusions was the smallest. The main type of effective inclusions (nucleus of AF formation) was oxide with MnS shell. The statistical results indicated that the proportion of effective inclusions in case of Mg addition first was the largest among the three samples, which induced more AF formation.

Accelerated corrosion behavior of weathering steel Q345qDNH for bridge in industrial atmosphere

Weathering steel (WS) has an extensive use in steel bridge construction thanks to its satisfactory atmospheric corrosion resistance, low life cycle cost and good mechanical properties. In this paper, cyclic immersion corrosion experiment was carried out in simulated industrial atmospheric environment. The corrosion weight loss, macro morphology, rusting coat section, XRD and electrochemical characteristics of bridge weathering steel Q345qDNH and low alloy steel Q345qD were compared. The corrosion characteristics were identified and underlying corrosion inhibition mechanism of bridge weathering steel Q345qDNH were analyzed. The experiment and analysis results show that the rusting coat on the exterior of standard carbon steel is relatively loose and porous, and the main component is Fe3O4. The rusting coat of weathering steel is divided into internal and external layers under atmospheric corrosion, the outer rusting coat is loose primarily composed of γ – FeOOH and the inner rusting coat is uniform and dense, principally containing α – FeOOH. During the evolution of the rusting coat, the addition of trace alloy elements in weathering steel effectively promoted the transformation from γ – FeOOH to α – FeOOH, forming a more stable and condense inner rusting coat. It can potently isolate the corrosive medium from penetrating in and enhance the electrochemical corrosion resistance of rusting coat, so it possesses better corrosion resistance in atmospheric corrosion environment and has a promising application prospect in bridge engineering construction.

Characterization of properties of Vanadium, Boron and Strontium addition on HPDC of A360 alloy

The demand for lighter weight decreased thickness and higher strength has become the focal point in the automotive industry. In order to meet such requirements, the addition of several alloying elements has been started to be investigated. In this work, the additions of V, B, and Sr on feedability and tensile properties of A360 has been studied. A mold design that consisted of test bars has been produced. Initially, a simulation was carried out to optimize the runners, filling, and solidification parameters. Following the tests, it was found that V addition revealed the highest UTS but low elongation at fracture, while B addition exhibited visa verse. On the other hand, impact energy was higher with B additions.

Zn-Mg and Zn-Cu alloys for stenting applications: From nanoscale mechanical characterization to in vitro degradation and biocompatibility

In the recent decades, zinc (Zn) and its alloys have been drawing attention as promising candidates for bioresorbable cardiovascular stents due to its degradation rate more suitable than magnesium (Mg) and iron (Fe) alloys. However, its mechanical properties need to be improved in order to meet the criteria for vascular stents. This work investigates the mechanical properties, biodegradability and biocompatibility of Zn-Mg and Zn-Cu alloys in order to determine a proper alloy composition for optimal stent performance. Nanoindentation measurements are performed to characterize the mechanical properties at the nanoscale as a function of the Zn microstructure variations induced by alloying. The biodegradation mechanisms are discussed and correlated to microstructure, mechanical performance and bacterial/cell response. Addition of Mg or Cu alloying elements refined the microstructure of Zn and enhanced yield strength (YS) and ultimate tensile strength (UTS) proportional to the volume fraction of secondary phases. Zn-1Mg showed the higher YS and UTS and better performance in terms of degradation stability in Hanks’ solution. Zn-Cu alloys presented an antibacterial effect for S. aureus controlled by diffusion mechanisms and by contact. Biocompatibility was dependent on the degradation rate and the nature of the corrosion products.

Solubility of Cu, Ni, Mn in Boron-Rich Fe-B-C Alloys

In the present study, the microstructure development and mechanical properties of the cast boron-rich Fe–B–C alloys cooled at 10 and 103 K/s were investigated as functions of alloying elements additions. These alloys were prepared in the following compositional ranges: B (10–14 wt.%), C (0.1–1.2 wt.%), M (5 wt.%), where M – Cu, Ni or Mn, balance Fe. Structural properties were characterized by quantitative metallography, X-Ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy. Mechanical properties of the structural constituents, such as microhardness and fracture toughness, were measured by a Vickers indenter. Copper becomes negligibly incorporated into the phases Fe(B,C) and Fe2(B,C) of the Fe–B–C alloys, but solubility limit forces the remaining solute into the residual liquid. As a result, the globular Cu inclusions are seen in the structure. As compared with copper, nickel has higher solubility in the constituent phases, with preferential solubility observed in the Fe2(B,C) crystals, where Ni occupies Fe positions. Having limited solubility, nickel also forms secondary Ni4B3 phase at the Fe2(B,C) boundaries. Manganese was found to dissolve completely in the Fe–B–C alloys forming substitutional solid solutions preferentially with Fe(B,C) dendrites. By entering into the iron borides structure, Mn and Ni improve their ductility but lower microhardness. The peculiarities in the structure formation and properties of the doped boron-rich Fe–B–C alloys were explained with electronic structure of the alloying elements considered.

Mechanical and thermo-physical properties of rapidly solidified Al−50Si−Cu(Mg) alloys for thermal management application

Al−high Si alloys were designed by the addition of Cu or Mg alloying elements to improve the mechanical properties. It is found that the addition of 1 wt.% Cu or 1 wt.% Mg as strengthening elements significantly improves the tensile strength by 27.2% and 24.5%, respectively. This phenomenon is attributed to the formation of uniformly dispersed fine particles (Al2Cu and Mg2Si secondary phases) in the Al matrix during hot press sintering of the rapidly solidified (gas atomization) powder. The thermal conductivity of the Al−50Si alloys is reduced with the addition of Cu or Mg, by only 7.3% and 6.8%, respectively. Therefore, the strength of the Al−50Si alloys is enhanced while maintaining their excellent thermo-physical properties by adding 1% Cu(Mg).

Glass-Forming Ability and Thermal Properties of Al70Fe12.5V12.5X5(X = Zr, Nb, Ni) Amorphous Alloys via Minor Alloying Additions.

The Al70Fe12.5V12.5Ni5, Al70Fe12.5V12.5Zr5 and Al70Fe12.5V12.5Nb5 alloys were prepared via mechanical alloying. The influence of Zr, Nb or Ni addition on the glass-forming ability of Al-Fe-V amorphous alloys have been investigated. The structure of Al70Fe12.5V12.5Ni5 was amorphous and Al70Fe12.5V12.5Zr5 was not completely amorphous by transmission electron microscopy, selected area electron diffraction and differential scanning calorimetry. Different criteria were used to evaluate the influence of the addition of alloy elements on the Glass-forming ability. The Al70Fe12.5V12.5Ni5 amorphous alloys exhibits higher glass-forming ability and activation energies of crystallization. Comparison of the effective atomic size ratio and mixture enthalpy on the glass-forming ability of these amorphous alloys demonstrates that the effective atomic size ratio value becomes more significant than the values of mixture enthalpy.

Effects of Alloying Elements Additions on Ambient Temperature Performance of Al–Si–Cu–Mg Base Alloys

The present study was carried out to investigate the effects of Ni, Mn, Zr, and Sc additions, individually or in combination with other additives, on the microstructure and tensile properties of 354 casting alloy (Al—9wt%Si—1.8wt%Cu—0.5wt%Mg) at room temperature. Tensile tests were carried out in the as-cast, solution heat-treated, and aged conditions using different aging temperatures and times. Six alloys were prepared using the 354 alloy, comprising a) the base 354 alloy (G1) and five other alloys (G6 to G10) containing Ni, Mn, Sc, Zr, added individually or in combination, and comprising one experimental alloy (G7) containing no copper. Among the alloys containing transition element additions (G6 through G10), the highest tensile and yield strength values are obtained with alloy G7 (2wt% Ni and 0.25wt% Zr but no Cu) in the as-cast and solution heat-treated conditions; alloys G8 and G10 also display a significant increase in tensile strength and ductility in the as-cast and solution heat-treated conditions. Solution heat treatment significantly improves strength and quality of these alloys even if they contain higher Fe and Mg levels compared to the base alloy. Holding the tensile samples of T6-treated G1 alloy resulted in a marked increase in the density of precipitated phase in the form of fine spherical particles. Increasing the holding time prior to deformation to 100 h resulted in the change in the morphology of the Al2Cu precipitates into thin platelets distributed in two perpendicular directions.

Influence of alloying elements on the thermal behavior of NiTi shape memory alloys

NiTi based shape memory alloys are one of the most intensely studied alloys from its class. Therefore, diverse commercial applications have been developed due to certain properties such as: shape memory effect, superelasticity and corrosion resistance. Currently, the main applications of NiTi alloys are automotive manufacturing and aerospace actuators, biomedical devices or pipe couplings. In recent years, NiTi shape memory alloys have been alloyed with a third element in order to improve the above-mentioned properties. In order to investigate the influence of the alloying elements on the thermal behavior of NiTi alloys, the addition of the third alloying element (Ta and Nb) is under investigation in the present study. The thermal behavior of the three alloys (NiTi, NiTiNb and NiTiTa) was studied by differential scanning calorimetry. Following the experiments, it was observed that the addition of the third alloying element influences the critical transformation temperatures.

Annealing Effect on the Microstructure and Mechanical Properties of AA 5182 Aluminum Alloy

Abstract The properties of aluminum alloys can be improved by the processing conditions that cause changes in the microstructure and by the addition of alloy elements. In order to understand the physical behavior and mechanical properties of aluminum alloys, it is important to be aware of some of the microstructural characteristics. Some of these characteristics are the morphology, alloy elements, volume and size, and second phase. In this study, we analyzed the effect of annealing on the mechanical and microstructural properties of the laminated AA 5182 aluminum alloy, when subjected to different annealing conditions. The alloy was heated to temperatures of 50o C, 100o C, 150o C, 200o C, 250o C and 300o C for 10 minutes and left to cool naturally. The evolution of the microstructure was characterized by optical and electronic microscopy with EDS, and, to obtain the mechanical properties, a tensile test was performed and the fractures were subsequently analyzed. The results showed that the heat treatment used reduced the amount of second phase particles and this influenced the mechanical properties.