Alloy Deposition Research Articles

Microstructure and mechanical properties of Ti6Al4V alloys fabricated by additive friction stir deposition

The additive friction stir deposition (AFSD) of Ti6Al4V alloy was successfully performed over a wide processing window. The microstructures were examined based on the high atemperature β grain size, grain boundary α formation and the propensity of variant selection as a function of process parameters. The analysis revealed that a reduction in deposition temperature could be achieved by the change in AFSD parameters, resulting in major reduction of prior β grain size and refinement of as-deposited α phase structure. This resulted in significant improvements of ductility and strength in the as-deposited state with ductility values up to ∼20% and maximum yield and ultimate tensile strengths values of 1010 MPa and 1233 MPa, respectively.

A study of dielectrics generated by electro-less electrochemical method for semiconductor devices

The aim of this work is to the basic concepts of the varies chemical and electrochemical procedures used m the fabrication of semiconductor devices seems to be useful to provide a suitable background for the present work, a brief review of the same as also the results obtained by earlier workers has been undertaken at the outset. A careful scrutiny of the results obtained by different workers reveals that although the aforesaid methods have a few limitations, they may be satisfice borily used as an alternative to sputter and evaporation techniques for device fabrication. The author carried out experimental investigations on the formation and properties of ohmic contact to silicon using two electroless plating baths - one operated at room temperature and the other at 95°C. In particular, the variation of contact resistance of ohmic contacts formed by electroless Ni-P process on silicon was studied as a function of sintering temperatures with operating point temperatures and pH of the baths as parameters. ^rom these studies it has been shown that both the baths yielded an adherent and dense deposit of nickel-phosphorous alloy on n-Si, which when sintered at very high temperatures give a less value of contact resistance due to the formation of metal-n -n contact. The phosphorous component of the Ni-P deposit diffuses into n-Si during heat treatment and forms the metal-n+ --n contact which behaves as an ohmic contact. As expected, the value of contact resistance was found to decrease with the increase of phosphorous materials in the deposit. The most favourable temperature range of heat treatment was found to be between 600°-700°C. Heats studying above 700°C slightly less increase the contact resistance probably due to the out diffusion of phosphorous from the Ni-P deposit. The barrier height and ideality factor are two important parameters for m-s contacts. The values of these two parameters of electrochemically fabricated Schottky diodes as obtained from the capacitance and current voltage characteristics were found to be in fairly close agreement with those of vacuumevaporated diodes. It is therefore, concluded that the electrochemical method of metal deposition is a valid and convenient technique for the fabrication and study of metalsemiconductor contacts

Powder Metallurgy Route for the Synthesis of Multiprincipal Element Alloys Sputtering Targets

Sputter deposition of multiprincipal element alloys (MPEAs) is a relatively new field of research with high functional potential. The multicomponent design space is immense and practically unexplored. An important obstacle for academic research of such sputtered films is the availability of single‐alloy targets and technical difficulties in using cosputtering of multiple metal targets or powder targets. This article focuses on the development of a simple powder metallurgy route, including cold uniaxial pressing of powder mixtures followed by pressureless sintering, for the preparation of targets made of two common base alloys forming simple solid solutions, i.e., FeNiCrCo and FeNiCrMn. In addition, targets of the former one containing 10 at% Al are also prepared. The sintered pellets are composed of randomly oriented crystallites with face‐centered cubic structures and an optimum chemical homogeneity. Oxide inclusions and residual porosity, inherent to consolidation and sintering of metal precursors, are observed and possible solutions to overcome these challenging problems are discussed. Nevertheless, encouraging results from preliminary deposition tests of FeNiCrCoAl0.4 using both direct current magnetron sputtering (DCMS) and high‐power impulse magnetron sputtering (HiPIMS) are presented.

Preparation and Properties of Electrodeposited Ni-B-Graphene Oxide Composite Coatings.

With the rapid development of modern industries, the surface quality and performance of metals need to be improved. Composite electrodeposition (co-deposition) has evolved as an important technique for improving the surface performance of metal materials. Herein, a new type of graphene oxide (GO)-reinforced nickel–boron (Ni-B) composite coating was successfully prepared on a 7075 aluminum (Al) alloy by co-deposition. Characterization revealed a significant improvement in the mechanical and anti-corrosion properties of the composite with the incorporation of GOs. The composite showed a rougher, compact, cauliflower-like morphology with finer grains, a higher hardness (1532 HV), a lower rate of wear (5.20 × 10−5 mm3∙N−1∙m−1), and a lower corrosion rate (33.66 × 10−3 mm∙y−1) compared with the Ni-B alloy deposit (878 HV, 9.64 × 10−5 mm3∙N−1∙m−1, and 116.64 × 10−3 mm∙y−1, respectively). The mechanism by which GOs strengthen the Ni-B matrix is discussed.

Effect of electrodeposition parameters and tungsten content on properties of Ni-Fe-W alloy deposits and its process cost analysis

Effect of electrodeposition parameters and tungsten content on properties of Ni-Fe-W alloy deposits and its process cost analysis

Initial stages of electrocrystallization of nickel, iron and nickel-iron alloy on a glassy carbon electrode in an electrolyte based on a eutectic mixture of choline chloride and ethylene glycol

The kinetics and mechanism of the initial stages of electrocrystallization of nickel, iron and nickel-iron alloy were characterized for the process of electrolytic deposition from a solution based on deep eutectic solvent ethaline (liquid mixture containing choline chloride and ethylene glycol at a molar ratio of 1:2, respectively). The theoretical model developed by Scharifker and Hills was used to interpret the obtained experimental data. It was shown that the electrodeposition of nickel and iron obeys the patterns of three-dimensional instantaneous and progressive nucleation, respectively. It was concluded that the formation of iron nuclei occurs at a significantly lower rate than in the case of nickel. The kinetics of the initial stages of Ni–Fe alloy deposition obeys the mechanism of instantaneous nucleation. Thus, in the case of electrolytic deposition from ethaline-based solutions on a glassy carbon electrode, nickel imposes on iron not only its own region of electrode potentials where alloy deposition occurs, but also the type of mechanism of nucleation in the course of codeposition.

Технология химического никелирования поверхностей изделий

When studying how a coating influences the wear resistance of details made of aluminum alloys in production conditions, we conducted a multifactorial experiment. The research has been carried out on the application of nickel-phosphorus coating on the surface of parts made of aluminum alloys, as well as the prefinishing treatment under coating. The parameters influencing the rate of nickel-phosphorus alloy deposition and modes of part surface treatment under coating are selected. Experiment planning was carried out, which made it possible to develop optimal modes of deposition and coating composition for obtaining high quality parameters of its surface: roughness and wear-resistance. It has been established that increasing the concentration of hypophosphite (sodium salt of alkaline metal and hypophosphorous acid) increases the coating formation rate. Experimental studies on wear resistance of nickel-phosphorus coated and uncoated samples have been conducted. The study shows that nickel-phosphorus coated samples provide higher wear resistance under friction conditions in comparison with uncoated samples, and assumes that the uniformity of heterogeneous coating consisting of nickel and phosphorus is due to the uniform fine crystalline structure consisting of regular shape particles (faceted or rounded). The basic principles of chemical coating technology and mechanical engineering technology are used

Influence of processing parameters on final characteristics of Ni-P-MWCNT coatings produced by pulsed electrodeposition

ABSTRACT The aim of the present work is to study the effects of multi-walled carbon nanotubes (MWCNT) concentration and current density on the surface morphology, microhardness, and corrosion resistance of pulsed electrodeposited Ni-P-MWCNT composite coatings. Ni-P-MWCNT composite coatings were deposited on low-carbon steel substrates using different MWCNT concentrations, namely 0.5, 1.0, and 1.5 g L−1 under various current densities of 3, 4, and 5 A dm−2. The as-produced coatings were characterised using field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Vickers microhardness measurement, and electrochemical impedance spectroscopy (EIS). To determine the impact of post-heat treatment on the microstructure and microhardness of the coatings, the composite coatings were heat-treated at 400°C for 1 h. Change in the studied variables profoundly altered the final characteristics of the Ni-P deposits. While the incorporation of 1.0 g L−1 MWCNT enhanced the microhardness of the alloy deposit by 560 HV, the microhardness of the composite coating was further increased by 405 HV when it underwent post deposition-heat treatment. The corrosion resistance of the composite coating is about 4 times higher than that of alloy deposits. The optimum mechano-corrosion results were obtained for Ni-P-1.0 g L−1 MWCNT coating fabricated under current density of 4 A dm−2.

Control of wire melting behavior during laser hot wire deposition of aluminum alloy

Laser wire deposition (LWD) is a promising method with a great potential for the fabrication of large open-frame components. Using hot wire in such a process, referred to as laser hot wire deposition (LHWD) would improve the laser absorption and deposition rate. In this work, the LHWD process of aluminum-alloy wire was studied with particular attention to the wire transfer behaviors. The results show that the wire melting rate could still be effectively increased even for the low-resistivity aluminum wire. The preheating current has a great influence on the wire transfer dynamics. Analysis demonstrates that the key to maintaining stable wire melting and transfer is to control the wire tip temperature by matching the wire feed speed and preheating current under certain laser power. A model computing the dynamic preheating process was established to predict the wire tip temperature with or without resistance preheating. A criterion based on the predictions was proposed to determine the optimal match of wire feed speed and wire preheating current, and thereby provided a deeper understanding of LHWD process.

The influence of laser directed energy deposition (DED) processing parameters for Al5083 studied by central composite design

Laser directed energy deposition (DED) of high-quality structural Al-based alloys is challenging due to the inherent physical and thermal properties of the Al powder feedstock. Therefore, an in-depth understanding of the influence of the applied processing parameters on the characteristics of the deposited material is paramount if one is to attain optimal performance. The objective of this study is to investigate the influence of the dominant processing parameters (laser power, scan speed, powder mass flow rate (PMFR), and hatch spacing) on the geometrical characteristics (track's height and dilution) of Al5083 double tracks fabricated using Laser Engineered Net Shaping (LENS®). Central composite design (CCD) response surface methodology (RSM) was utilized to study the influence of the varied processing parameters and their interactions and to develop an empirical statistical prediction model for the studied responses. The results reveal that the applied PMFR has a strong influence on the deposited track's height (positive) and dilution (negative). The laser power at the first-order factor shows a weak influence for both studied responses. However, the interaction between the laser power and the hatch spacing shows significant effects on the track's height and dilution. The microstructure and microhardness of the as-deposited Al5083 double tracks are also discussed, as proxies to the anticipated performance of the deposited material.

Laser powder bed fusion of Zr-modified Al–Cu–Mg alloy: Crack-inhibiting, grain refinement, and mechanical properties

The application of laser powder bed fusion (L-PBF) in conventional high-strength wrought aluminum alloys is a significant challenge due to its high cracking sensitivity. In this study, 2024Al and 1.3-wt% Zr-modified 2024Al alloy deposits were prepared by L-PBF using pre-alloyed powder. The solidification cracking susceptibility of the 1.3-wt% Zr-modified 2024Al alloy was reduced to ∼0.4 of that of the 2024Al alloy. Compared to the complete columnar α-Al grain microstructure in the 2024Al deposit, the crack-free Zr-modified 2024Al deposit exhibited a heterogeneous grain structure having columnar α-Al grains in the inner region of the molten pool and ultrafine α-Al equiaxed grains at the fusion boundary. Based on the time-dependent nucleation theory and constitutional undercooling analysis ahead of solidification interface, the precipitation behavior of primary Al3Zr nanoparticles is analyzed, and it is deduced that the high intensity of effective nucleation sites by nanosized primary Al3Zr at the fusion boundary of molten pool leads to the formation of equiaxed grains at the beginning of the solidification of molten pool. The as-deposited Zr-modified 2024Al exhibited a yield strength (YS) of ∼376 ± 7 MPa and an ultimate tensile strength (UTS) of 441 ± 7 MPa with an elongation of 14.1 ± 1.6%. The YS and UTS increased to 402 ± 9 MPa and 483 ± 37 MPa after T6 heat treatment, respectively. Both the tensile properties of the as-deposited and T6-treated Zr-modified 2024Al were comparable to the wrought 2024-T651 alloy and higher than most of the previous L-PBFed Al–Cu–Mg alloys.

Heat Accumulation, Microstructure Evolution, and Stress Distribution of Ti–Al Alloy Manufactured by Twin‐Wire Plasma Arc Additive

Herein, the deposition of a Ti–Al(48 at%) alloy via twin‐wire arc additive manufacturing (WAAM) using plasma arc welding (PAW) and tungsten inert gas (TIG) welding arc sources is presented. The microstructure and the phase composition of different regions of the alloy are analyzed using metalloscopy and X‐ray diffraction. The transient temperature field and residual stress distribution are measured before and after the process, respectively. A transient thermostress model is established using the finite‐element method. Results show that the alloy is composed primarily of α2‐Ti3Al and γ‐TiAl phases, while the microstructure evolution during the Ti–Al(48 at%) alloy deposition process is described. The thermal conductivity in the lower region of the alloy far exceeds that in the middle and upper regions. The thermal conductivity is smaller in the upper region and the midregion, resulting in the increase in heat accumulation. Due to arc shrinkage and reduced heat input, the PAW process reduces the heat accumulation and stress distribution differences more effectively than the TIG process.

Inconel 718-W7Ni3Fe bimetallic structures using directed energy deposition-based additive manufacturing

ABSTRACT Bimetallic structures produced via additive manufacturing (AM) have demonstrated outstanding potential for improving the properties of high-temperature structures. To this end, it was hypothesised in this study that using a tungsten alloy would increase the thermal conductivity of the bimetallic structure compared to pure Inconel 718. Bimetallic structures of Inconel 718 and W7Ni3Fe were manufactured using directed energy deposition (DED)-based AM. Hardness, thermal analysis by diffusivity measurement, and compression testing were done to evaluate the effect of tungsten alloy deposition on Inconel 718's thermal and mechanical properties. Bimetallic structures of Inconel 718-W alloy containing a 50–50 volume % of each displayed a 100% improvement in thermal diffusivity compared to pure Inconel 718, with extensive mixing and remelting due to laser processing. Furthermore, the bimetallic compression samples showed a 100% increase in yield strength combined with a 50% reduction in modulus of elasticity compared to Inconel 718.

Wire-Arc Directed Energy Deposition of Aluminum Alloy 7075 with Dispersed Nanoparticles

Wire-Arc Directed Energy Deposition of Aluminum Alloy 7075 with Dispersed Nanoparticles

Wire-Arc Directed Energy Deposition of Aluminum Alloy 7075 with Dispersed Nanoparticles

Wire-Arc Directed Energy Deposition of Aluminum Alloy 7075 with Dispersed Nanoparticles

Laser Remelting Process Simulation and Optimization for Additive Manufacturing of Nickel-Based Super Alloys.

Nickel-based super alloys are popular for applications in the energy and aerospace industries due to their excellent corrosion and high-temperature resistance. Direct metal deposition (DMD) of nickel alloys has reached technology readiness for several applications, especially for the repair of turbomachinery components. However, issues related to part quality and defect formation during the DMD process still persist. Laser remelting can effectively prevent and repair defects during metal additive manufacturing (AM); however, very few studies have focused on numerical modeling and experimental process parameter optimization in this context. Therefore, the aim of this study is to investigate the effect of determining the remelting process parameters via numerical simulation and experimental analyses in order to optimize an industrial process chain for part repair by DMD. A heat conduction model analyzed 360 different process conditions, and the predicted melt geometry was compared with observations from a fluid flow model and experimental single tracks for selected reference conditions. Subsequently, the remelting process was applied to a demonstrator repair case. The results show that the models can well predict the melt pool shape and that the optimized remelting process increases the bonding quality between base and DMD materials. Therefore, DMD part fabrication and repair processes can benefit from the remelting step developed here.

On the Effect of Heat Input and Interpass Temperature on the Performance of Inconel 625 Alloy Deposited Using Wire Arc Additive Manufacturing–Cold Metal Transfer Process

Relatively high heat input and heat accumulation are treated as critical challenges to affect the qualities and performances of components fabricated by wire arc additive manufacturing (WAAM). In this study, various heat inputs, namely 276, 552 and 828 J/mm, were performed to fabricate three thin-wall Inconel 625 structures by cold metal transfer (CMT)-based WAAM, respectively, and active interpass cooling was conducted to limit heat accumulation. The macrostructure, microstructure and mechanical properties of the produced components by CMT were investigated. It was found that the increased heat input can deteriorate surface roughness, and the size of dendrite arm spacing increases with increasing heat input, thus leading to the deterioration of mechanical properties. Lower heat input and application of active interpass cooling can be an effective method to refine microstructure and reduce anisotropy. This study enhances the understanding of interpass temperature control and the effectiveness of heat inputs for Inconel 625 alloy by WAAM. It also provides a valuable in situ process for microstructure and mechanical properties’ refinement of WAAM-fabricated alloys and the control of heat accumulation for the fabrication of large-sized structures for future practical applications.

Features of design, construction and technology of manufacturing galvanoplastic jewellery

The features of design, construction and manufacturing technology of electroplated jewellery are considered. The classification of jewellery made by the method of electroforming, based on their areas of application, is presented. The technological features of the formation of the surface of products with a “posi-tive” and “negative” build-up of the deposited metal, ways of reducing the roughness of the deposited coat-ings with an increase in their thickness are considered. Methods of creating suspension and fastening ele-ments of the product structure are described. The main modern trends in the development of technology and design of products made by the method of electroforming are considered: the use of 3D technologies in the development and creation of models, the use of conductive polymer compositions for the manufacture of models, computerization of the technological process of forming metal deposits of precious alloys of a cer-tain carat and colour. Modern technological methods allow raising the level of electroplated jewellery de-sign to a new level.

Phase composition and concentration of yttriumin films during the deposition of aluminumand aluminum alloys from the gas phase

The work is devoted to the study of the stabilizing effect of yttrium additions during the deposition of thin aluminum films, which are used for the manufacture of elements of micro- and nanoelectronic devices. The surfaces of Al films doped with aluminum oxide were investigated using a scanning electron microscope before and after annealing for 300420 s at a temperature of 500 C. It is shown that fine alumina particles are uniformly distributed on the surface of the films during thermal evaporation of a wire made of an Al Al2O3 alloy. By the method of quantitative metallography, the content of the AlxOy phase in the Al films was determined: when spraying wire from the Al Al2O3 alloy, its content was 1012% of the mass fraction; when spraying wire made of Al Al2O3 alloy and Al wire in a ratio of 50:50 1% mass fraction.

Effect of the structure and morphology of Ni-based porous deposits on their electrocatalytic activity towards hydrogen evolution reaction

Porous nickel and nickel-cobalt alloy deposits were obtained by electrodeposition on a dynamic hydrogen bubble template. Deposition was carried out from chloride electrolytes in a galvanostatic mode at a current density of 0.3 A/cm2. The porosity of the obtained deposits is associated with the macro- and micropores. It was found that the nickel and nickel-cobalt alloy deposits feature by different porous layer structures. In case of nickel, a typical foam structure is formed, while the Ni–Co alloy deposit morphology is more like loose (powder) metals. The total porosity of the obtained structures calculated based on experimental data decreased with the deposit thickness: from 0.4 to 0.1 for nickel foams, and from 0.9 to 0.8 for the Ni–Co deposit. It was shown that the dependences of the macropore number and the fraction of the surface occupied by them can be approximated by lognormal distribution. The agreement between the experimental values and values calculated by approximating equations indicates the stochastic nature of the macropore system formation. The catalytic properties of the obtained porous deposits toward the hydrogen evolution reaction in alkali were investigated. It was found that the decrease in the hydrogen evolution potential in comparison with a smooth electrode reaches 370 mV for nickel foams, and 440 mV for porous Ni–Co alloy deposits. However, the high porosity of the Ni–Co alloy caused poor adhesion of the deposit to the substrate; therefore, the porous Ni–Co deposit cannot be used without further strengthening. The dependences of the depolarization value during hydrogen evolution on the average diameter of pores, their number, and the macropore fraction were analyzed. Optimal properties of foams that reduce the potential of hydrogen evolution in alkali are as follows: pore diameters from 30 to 50 μm and their quantity from 50 to 100 pcs/mm2.