Nickel-based Powder Research Articles

Thermodynamic calculation and machine learning aided composition design of new nickel-based superalloys

At present, the operating temperature of the fourth-generation of nickel-based powder superalloys has not reach the target of 815 °C, and the traditional superalloy design and optimization methods are costly and inefficient. To overcome these challenges, phase diagram is used to calculate the thermodynamic parameters of the typical first three generations of nickel-based powder superalloys and representative fourth-generation superalloys. From strengthening processes including solid solution strengthening and γ′ phase strengthening, the effects of alloy compositions on alloy characteristics are examined. Based on this analysis, the thermodynamic standards that satisfy the performance requirements of the fourth-generation nickel-based powder superalloys are established. Then, the standards are applied to JMatPro and machine learning techniques as the foundation for determining the composition selection range, and several new nickel-based superalloys are created. The machine learning aided alloy design concept and theoretical results will provide significant guidance for further study of new nickel-based superalloys.

Homogeneity, Hardness Distribution, and Metallurgical Behavior of SS-304 Cladding Surface with Si, Ni, and TiO2

ABSTRACT In the present study, an attempt was made to develop surface cladding on SS-304 steel by utilising a mixture of EWAC (70% nickel-based powder as an early warning and caution), 20% Si, and 10% TiO2 (Titanium dioxide) powder via microwave energy. The microwave cladding process on the SS-304 (stainless steel-304) was carried out in the in-house developed set-up on the microwave. The microwave cladding process was carried out at 900 W with a 2.45 GHz frequency for 120 s. The microstructure image of the developed surface showed the presence of TiO2 particles. A uniform cladding layer with fewer dark pixels has been observed. Higher homogeneity of the cladding layer and cladding surface reduces the dimensional deviation of the developed cladding surface. The XRD of the cladding surface shows the presence of FeNi3, NiSi2, Ni3C, NiC, Ni2Si, FeNi, and TiO2 phases. Uniform hardness distribution for the cladding layer and cladding surface was observed, while hardness distribution in SS-304 after solidification a severe variability. The hardness of SS-304 was improved by about 42.42% after the microwave cladding of Ni, 20% Si, and 10% TiO2. The main reason for the increase in hardness is the formation of different hard phases such as Ni3C, NiC, and TiO2 phases.

A crack growth model for nickel-based powder metallurgy superalloy considering creep zone at crack tip

In this paper, the creep crack growth behavior of powder alloy materials for turbine disks was studied. The experimental results show that the creep crack growth rate at 700 ℃ is significantly higher than that at 600 ℃, and the main form of the crack growth is intergranular fracture. It is found that there is an obvious dispersion state in the early stage of creep crack growth, which cannot be described by creep fracture parameters based on the linear elastic assumption, such as C(t),Ct. To solve this problem, a rate model considering creep zone at crack tip was proposed, which can describe the crack growth rate curve uniformly. The prediction deviation of creep crack growth time is approximately 1.5X.

Influence of Deformation Rate on Nucleation and Growth of Recrystallized Grains during Hot Deformation of Nickel-Based Powder Superalloys

High temperature uniaxial compression deformation test was carried out on nickel-based powder superalloy FGH96 alloy by thermal processing simulation test machine, and the relationship between grain boundary characteristics and nucleation mechanism of recrystallized grains, growth characteristics of recrystallized cores and related dynamic softening mechanisms was studied. According to the correlation and evolution law of grains, combined with the change trend of grain orientation during the deformation process, the recrystallization behavior characteristics of the grains with special orientation generated during the deformation process were analyzed. When the deformation temperature is 1070 °C, the evolution rules of the substructure grain boundaries with an orientation difference of less than 10° are different under different deformation rate conditions, which indicates that the dynamic softening mechanism of FGH96 alloy is slightly different with the increase of deformation rate. There are different. With the increase of the deformation rate, the nucleation mechanism induced by Σ3 twinning gradually replaced the nucleation mechanism of continuous subgrain rotation and coarsening, and the grain growth rate gradually slowed down.

Grain Size Evolution of Nickel-Based Superalloys after Hot Deformation

In this work, the uniaxial compression deformation test of nickel-based powder superalloys was carried out in a vacuum isothermal adiabatic environment using the Thermocmaster-Z thermal processing simulation test machine. The evolution of the microstructure in the two stages of dynamic softening and strain hardening in the true stress-true strain curve in the process, including the interaction of grain size, local misorientation and their relative mobility. During most of the plastic deformation time, the flow stress is gradually increased, that is, the strain hardening dominates, while in the remaining plastic deformation process parameters, dynamic softening dominates. Under different plastic deformation process parameters, The average grain size fluctuates to a certain extent under the condition of partial strain values, but the final evolution law is gradually decreasing, while the final trend of the average local misorientation is increasing.

Effect of Semi-Aging Heat Treatment on Microstructure and Mechanical Properties of an Inertia Friction Welded Joint of FGH96 Powder Metallurgy Superalloy

Inertia friction welded joints often present different microstructures than the base metal, and subsequent heat treatment processes are always needed to maintain superior performance. This study investigates the effect of semi-aging heat treatment after welding on the microstructure, residual stress, micro-hardness, and tensile properties of inertia friction welded FGH96 powder metallurgy superalloy using optical microscopy, scanning electron microscopy, X-ray diffraction, and hardness and tensile tests. The results show that the semi-aging heat treatment after welding does not affect the grain size or grain morphology of the base metal. However, the recrystallization process can be further promoted in the weld nugget zone and transition zone. Meanwhile, the grain size is refined and the residual stress is significantly reduced in the welded joint after the same heat treatment. Under the synergetic strengthening effect of the γ′ phase, semi-aging heat treatment increased the micro-hardness of the weld nugget zone from 470 HV to 530 HV and improved the average tensile strength at room temperature by 118 MPa. These findings provide a reference for the selection of the heat treatment process after inertia friction welding of nickel-based powder metallurgy superalloys.

Исследование содержания кислорода и азота в плазменных покрытиях на основе никеля

Studies were carried out on the oxygen and nitrogen content of nickel-based powders and plasma coatings therefrom. The Ni-based sprayed materials were divided into four groups according to the mechanism of their interaction with oxygen. The first group includes Ni, the second alloys alloyed with Cr, the third additionally alloyed with Al, the fourth alloys having more complex alloying with Cr, C, B, Si elements that actively interact with oxygen, including with the formation of gaseous oxides. Alloying 20 % Cr reduces the oxygen content of the coating by 35 %, alloying 17 % Cr – 10 % Al reduces the oxygen content of the coating by 57 %, more complex alloying 13.5 % Cr – 2.7 % Si – 1.65 % B – 0.36 % C — reduces the oxygen content of the coating by 92 %. Increasing the plasma jet power increases the oxygen content of the Ni20Cr coating from 0.55 to 1.6 %. Increasing the plasma jet power and preheating the substrate prior to sputtering results in a limited increase in the oxygen content of Ni – 17 % Cr – 10 % Al – 1 % Y and Ni – 15 % – Cr 4 % – Fe 0.8 % C – 4.1 % Si — 3.1% B coatings using a plasma nozzle to eliminate the thermal effects of the plasma jet. The Ni – 17 % Cr – 10 % Al – 1 % Y coating sprayed with the nozzle contains 0.48 % O and 0.14 % N instead of 2.31 % O and 0.37 % N when sprayed without the nozzle. An increase in the oxygen and nitrogen content in the coatings Ni, Ni – 20 Cr and Ni – 40 Cr together with the formation of a liquid-hardened structure in these coatings determines an increase in microhardness relative to the value for the powder by 1.6 – 1.9 times.

Comparative Study of Prior Particle Boundaries and Their Influence on Grain Growth during Solution Treatment in a Novel Nickel-Based Powder Metallurgy Superalloy with/without Hot Extrusion

The prior particle boundaries (PPBs), as one of the typical defects in the nickel-based powder metallurgy superalloy, largely affect the microstructure and thus properties/performance of alloys. However, the effect of PPBs on the microstructure evolution in nickel-based powder metallurgy superalloy during heat treatment is still unclear. In this paper, a comparative study of PPBs and their influence on grain growth during solution treatment in a novel nickel-based powder metallurgy superalloy FGH4113A (i.e., WZ-A3 from Shenzhen Wedge, China) with/without hot extrusion (HEX) was conducted. Firstly, through a combination of scanning electron microscope (SEM), electron probe microanalyzer (EPMA) and transmission electron microscope (TEM) techniques, PPBs in FGH4113A alloys were characterized to be Al2O3, carbides (TiC, M6C, M23C6) and large-size γ′ particles. After HEX, the oxides broke, carbides deformed, and γ′ phase redistributed. After solution treatment at 950 °C, the TiC decomposed to M6C and M23C6, while no such decomposition occurred in FGH4113A alloys after solution treated at 1050 °C and 1150 °C. Secondly, the evolution of grain size in FGH4113A alloys was analyzed using the electron backscattered diffraction (EBSD) technique. At 950 °C, the decomposition of carbide TiC resulted in the increase of PPBs and the enhancement of their pinning effect on grain boundaries, thus inhibiting grain growth. At 1050 °C, the nucleation rate due to recrystallization is comparable to the grain growth rate, leading to the stable distribution of grain size. While at 1150 °C, the higher temperature can induce a higher content of PPBs. However, the driving force for grain growth surpassed the pinning force of PPBs, making the grains quickly coarsen. Finally, it was concluded that the HEX process is an effective method to modify the microstructure of powder metallurgy superalloy after HIP that can heavily refine the grains in the powder metallurgy superalloys. Furthermore, based on the present experiment and analysis, an appropriate solution treatment mechanism (i.e., 1050 °C for 2 h) was proposed for FGH4113A alloys.

Gaussian process regressions on hot deformation behaviors of FGH98 nickel-based powder superalloy

The hot deformation behaviors of FGH98 nickel-based powder superalloy were experimentally investigated and theoretically analyzed by Arrhenius models and machine learning (ML). Hot compression tests were conducted with a Gleeble-3800 thermo-mechanical simulation machine on the FGH98 superalloy at strain rates of 0.001–1 s–1 and temperatures of 1025–1175 °C. The peak stresses under different deformation conditions were analyzed via the Sellars model and an ML-inspired Gaussian process regression (GPR) model. The prediction of the GPR model outperformed that from the Sellars model. In addition, the stress-strain responses were predicted by the GPR model and tested by experimentally measured stress-strain curves. The results indicate that the developed GPR model has great power with wide generalization capability in the prediction of hot deformation behaviors of FGH98 superalloy, as evidenced by the R2 value higher than 0.99 on the test dataset.

Results of Studying the Profile of Single Tracks of Coatings Produced from Aluminum- and Nickel-Based Powders

Results of Studying the Profile of Single Tracks of Coatings Produced from Aluminum- and Nickel-Based Powders

Results of studying the profile of single tracks of coatings produced from aluminum and nickel-based powders

The profiles of individual tracks were experimentally studied considering the powder flow rate, nozzle speed and temperature when creating a coating from a monometallic aluminum powder, a mixture of two monometallic powders of the aluminum-nickel and nickel-titanium systems, as well as composite powder from a mixture of monometallic powder of aluminum and corundum. Aluminum and nickel powders were chosen as the investigated ones, since they are the basis for most functional coatings. The dependence of the track profile on the scanning speed is established, the step between the tracks is determined, which ensures uniform coverage.

Turning/Shot peening of Nickel-based powder metallurgy superalloy: Effect on surface integrity and high-temperature low-cycle fatigue properties

In this study, a nickel-based powder metallurgy alloy was processed via turning, ceramic bead peening, and shot peening by high-intensity cast-iron shots and low-intensity ceramic beads (denoted as compound shot peening). We investigated the surface morphology (surface stress concentration factor, Kst), the surface residual stress profile, microstructure, and the hardness gradient of three surface states and compared the high-temperature low-cycle fatigue lives. The results showed that the surface stress concentration coefficients after turning, ceramic bead peening, and compound shot peening were 2.39, 1.98, and 2.12, respectively. The average surface roughness, Sa, after turning was low, but the bottom of the tool mark was sharp, so the Kst value was higher than that after shot peening, which formed a round bottom by bead blasting. Compared with ceramic bead peening, a surface structure with a deeper compressive residual stress profile and a higher hardness gradient was formed after compound shot peening, and nanostructured features appeared on the outermost surface. The estimated low-cycle fatigue lives after the ceramic bead peening and compound shot peening were 0.99 and 3.13 times longer than after the turning process respectively with strain amplitude 0.5% at 538℃. Moreover the gain of compound shot peening on low cycle fatigue performance gradually decreases with the increase of the strain amplitude.

Експериментальне дослідження впливу параметрів газодинамічного напилювання на коефіцієнт використання порошку

The effect of temperature and air pressure at the supersonic nozzle inlet, as well as the distance from the nozzle outlet to the surface of the substrate (stand-of-distance) on the powder usage rate of nickel-based powder in low pressure cold gas-dynamic spraying (inlet pressure up to 1.0 MPa) was analyzed. One of the most important parameters characterizing the deposition efficiency of the spraying process is the powder usage rate. This parameter is the ratio of the mass of the coating to the mass of the powder used to obtain this one. For the process of cold gas-dynamic spraying, implemented on the equipment using air pressure up to 1.0 MPa, the main disadvantage is the relatively low-powder usage rate. To increase it (but not limited to it), a ceramic component, such as alumina Al2O3, is added to pure metal powders. In this study a nickel-based powder mixture, in which the content of Al2O3 powder is about 10% mass., was used. Titanium alloy plates BT9 were used as the substrate material. Based on the multifactor planning of the experiment, the effect of the complex parameters of the low-pressure cold gas-dynamic spraying on the powder usage rate was studied. After the coating deposition according to the matrix of the experiment, the samples with coatings were weighed. According to the known mass of the samples before spraying and the increase in their mass, the powder usage rate was calculated. From the analysis of the obtained statistical data, the dependence of the effect of the complex parameters of the deposition process on the powder usage rate was developed. The maximum value of the powder usage rate were obtained up to 35 %. It was confirmed that the air temperature at the nozzle inlet has the greatest effect on the above-mentioned parameter. The explanation of this is the increase in gas flow temperature and velocity, and as a result, the increase in the velocity and temperature of the powder particles in this flow. Higher values of the velocity and temperature of the particles lead to more intense plastic deformation of particles during impact with the substrate and their adhesion to it.

Effects of intermediate temperature on the grain boundary and γ' precipitates of nickel-based powder superalloy under interrupted cooling

The serrated grain boundaries obtained by solution treatment followed by slow-cooling can improve the creep properties of nickel-based superalloy, but such heat treatment simultaneously gives rise to coarse γ' precipitates and deteriorates the high-temperature strength. Herein, the interrupted cooling during solution treatment was used to obtain the serrated grain boundaries and the fine γ' precipitates in a nickel-based powder superalloy by regulating the intermediate temperature. The effects of intermediate temperature on the grain morphology and secondary γ' precipitate size distribution in the alloy were systematically investigated. Flat grain boundaries were formed in the sample at the intermediate temperature of 1140 °C. The serrated grain boundaries appeared in the samples with an intermediate temperature below 1120 °C. The amplitude of the serrated grain boundaries increased from 0.62 to 1.03 µm as the intermediate temperature reduced from 1120° to 1000°C. With the decrease of the intermediate temperature, the secondary γ' precipitates in the alloys changed from spherical to butterfly shapes, and then split. The size of secondary γ' increased from 312 to 456 nm for the alloys with the intermediate temperature between 1120 and 1000 °C. Meanwhile, the tertiary γ' precipitates were produced under the intermediate temperature of 1120–1050 °C, forming a multimodal size distribution of γ' precipitates in the superalloys. The microhardness values of the samples were improved with the increasing intermediate temperature during the interrupted cooling, which was closely related to the size of γ'. As the intermediate temperature rose from 1050 °C to 1120 °C, the tensile strength of the samples increased from 1297 MPa to 1425 MPa at room temperature and from 985 MPa to 1100 MPa at 650 °C.

Вирощування авіаційної деталі «Завихрувач» з жароміцного сплаву Inconel 718 за технологією селективного лазерного спікання

In order to solve the problems of improving the reliability and efficiency of aircraft engines, the paper considers as an alternative to traditional methods of obtaining aviation parts using additive production. According to the three-dimensional digital model (CAD/CAM/CAE-systems), additive technologies allow creating complex structures with high mechanical and operational characteristics. They must be complied with the standard ASTM F2792.1549323-1. The process of additive production is characterized by a sequence of operations: construction of a digital 3D–model → the choice of additive technology and its implementation → obtaining the finished part. In the work it is proposed to consider the possibility of growing the aircraft part «Swirler» from heat-resistant nickel alloy Inconel 718 by selective laser sintering technology in a 3D–printer type EOS M400 under the conditions of JSC «Motor Sich». Spherical nickel-based powders from Sino-Euro Materials Technologies of Xi'an Co., Ltd. were used as starting powder materials. (Sino Euro, China) and LPW Technology, Ltd (LPW, UK). The dependence of the mechanical and heat-resistant properties of the Inconel 718 alloy on the direction of growth of the part (in particular, the horizontal direction XY and the vertical direction Z) was established experimentally. Metallographic studies of Inconel 718 alloy samples before and after the heat treatment process were performed. With the help of Unigraphics NX 7.5, the modeling of an aircraft part was performed, which begins with the construction of a sketch, design of a digital 3D–model of the part and its editing. It is shown that the cultivation of the aviation part «Swirler» by the technology of selective laser sintering is characterized by: a smaller number of technological operations for the manufacture of «complex» in the geometric configuration of the part; reducing up to 6 times the lack of finished parts; reduction of material costs for equipment and additional machining; reduction to 12–17 % of the weight of the part in comparison with its metal analogue obtained by machining. Keywords: additive technologies, selective laser sintering, Inconel 718, 3D–model, aviation part.

Investigation of the effect of small iron and molybdenum additives on the phase composition of a titanium and nickel-based powder alloy

Information is presented on the study of the effect of small iron and molybdenum additives on the phase composition of a powder alloy based on titanium and nickel. The proposed method allows to increase the rate of carburization by 1.5...2 times compared to traditional charcoal carburetors.

Investigation of the effect of small iron and molybdenum additives on the phase composition of a titanium and nickel-based powder alloy

The article presents information on the study of the effect of small iron and molybdenum additives on the phase composition of a powder alloy based on titanium and nickel. The authors found that the presence of unreacted pure components (titanium and nickel) indicates the incompleteness of the diffusion interaction process and the need to adjust the sintering mode of porous samples. Additives of 2.5% and 4.0% iron, as well as 2% molybdenum act as an inhibitor on the sintering process of porous samples.

Formation of a joint between deposited and base metals during laser cladding of a nickel-based powder onto a copper-based alloy

The Paton Welding Journal, 2022, №04. International Scientific-Technical and Production Journal «The Paton Welding Journal» «The Paton Welding Journal» has been published monthly since 2000 in English, ISSN 0957-798X. «The Paton Welding Journal» is a cover-to-cover English translation of the «Avtomaticheskaya Svarka» (Automatic Welding) journal. The «Avtomaticheskaya Svarka» journal has been published monthly since 1948 in Russian, ISSN 005-111X.

Impact of Atomization Pressure on the Particle Size of Nickel-Based Superalloy Powders by Numerical Simulation.

Vacuum induction melting gas atomization (VIGA) has evolved as an important production technique of superalloy powders used in additive manufacturing. However, the development of powder preparation techniques is limited because the crushing process of gas-atomized metal melt is difficult to characterize by conventional experimental methods. Herein, we report the application of computational fluid dynamics to simulate the breaking behavior of droplets in the process of preparing nickel-based superalloy powders by VIGA, as well as the results on the effect of gas pressure on the atomization process and powder particle size distribution of metal melt. In the process of primary atomization, the crushing morphology of superalloy melt shows an alternate transformation of umbrella shapes and inverted mushroom cloud shapes, and with the increase in atomization pressure, the disorder of the two-phase flow field increases, which is conducive to sufficient breakage of the melt. Most importantly, in the process of secondary atomization and with the increasing atomization pressure, the particle size distribution becomes narrower, the median particle diameter and average particle size decrease, and the decreasing trend of the particle size increases gradually. The simulation results are compliant with the performed nickel-based superalloy powder preparation tests. This study provides insight into the production and process optimization of superalloy powder prepared by the VIGA method.

Effect of long-term aging on microstructure stability of a novel nickel base powder superalloy

The microstructure stability, evolution law and identification of carbide and harmful phase TCP of nickel-base powder superalloy aged at 800 ℃ for 100 h —10000 h were studied by means of field emission scanning electron microscope, atomic force microscope and electron backscatter diffraction. The results show that with the increase of aging time, the grain size changed little, the grain boundary coarsened and the twin boundary Σ3 increased first and then decreased. γ' phase coarsened obviously from 500 h aging, and the coarsening rate increased first and then decreased The coarsening mechanism is mainly the combination of adjacent γ' phase by AFM analysis. Lath-like σ phase CrCo precipitated at the grain boundary first after aging for 1000 h. When the aging time was up to 2000 h, the needle-like μ phase Co7(W, Mo)6 was observed in the crystal. With the further increase of aging time, the total content of TCP phase at grain boundary and in crystal increased obviously. However, at 10000 h, the TCP phase in the crystal and at the grain boundary almost disappeared, mainly because the atoms in the TCP phase diffused into the γ' phase to form a new solid solution and deposited on the grain boundary, which further coarsened the grain boundary.