Mechanical Alloying Parameters Research Articles

Simulation and study of the milling parameters on CuFeTaTiW multicomponent alloy

The CuFeTaTiW multicomponent alloy has been devised as an interlayer thermal barrier in nuclear fusion reactors. In order to predict the phase constitution of this alloy, two different lines of work were performed: (a) simulation using Molecular dynamics and Monte Carlo and (b) study of the influence of mechanical alloying parameters on the structures formed. The simulation results show that the most stable structure is achieved starting from a bcc type-structure and using Monte Carlo simulation. In fact, in these conditions the separation into two bcc phases Fe-Ta-W and Cu-Ti is predicted at room temperature. However, the experimental preparation of the materials with mechanical alloying revealed that from 2 h of milling a single bcc phase is formed. The structure of the milled powder was not much influenced by the amount of the process control agent and the by the size of the W starting particles, but generally there was formation of Ta2H from the reaction between the powders and the process control agent.

Experimental investigation and numerical modeling of mechanically alloyed Al-TiC composites

The present work studies the mechanical alloying, consolidation, evaluation, modeling, and optimization of the Al-TiC composites mixed at different milling times (MTs) of 6, 12, 24, and 48 h and reinforced with three TiC concentrations (3, 6, and 12 vol.%). The Al-TiC composites formed via the powder metallurgy method. The XRD of the mixed powder and the consolidated composites were investigated. Furthermore, density, wear, compressive strength, and hardness have been examined for the consolidated composites. Also, the worn surface of the wear-tested composites was studied utilizing SEM analysis. The response surface methodology (RSM) was involved to clarify the effects of mechanical alloying parameters of MTs and the TiC concentrations and their interaction towards achieving their optimum process factors to produce Al-TiC composites. The RSM results prove the applied factors’ importance in improving the consolidated composites’ properties. The optimization results show the optimum parameters to produce Al-TiC composites are 28.4 MTs and 12 vol.% TiC to produce Al-TiC composites with 304.4 ± 3 MPa compressive strength, 191.21 ± 2 HV hardness, 2.88 ± 0.008 g/cm3 density, and 9.7 ± 0.01 mg weight loss. The ANOVA analysis reveals that the suggested models can virtually expect the tested responses of density, hardness, compressive strength, and weight loss with a confidence level of over 90, 98, 95, and 95%, respectively.

Advanced Zinc-Magnesium Alloys Prepared by Mechanical Alloying and Spark Plasma Sintering.

Zinc and its alloys are considered as promising materials for the preparation of biodegradable medical devices (stents and bone fixation screws) due to their enhanced biocompatibility. These materials must achieve an ideal combination of mechanical and corrosion properties that can be influenced by alloying or thermomechanical processes. This paper presents the effects of different mechanical alloying (MA) parameters on the composition of Zn-1Mg powder. At the same time, this study describes the influence of preparation by MA on Zn-6Mg and Zn-16Mg alloys. The selected powders were compacted by the spark plasma sintering (SPS) method. Subsequently, their microstructures were studied and their mechanical properties were tested. The overall process led to a significant grain refinement (629 ± 274 nm for Zn-1Mg) and the formation of new intermetallic phases (Mg2Zn11, MgZn2). The compressive properties of the sintered samples were mainly related to the concentration of the alloying elements, where an increase in concentration led to an improvement in strength but a deterioration in ductility. According to the obtained results, the best properties were obtained for the Zn-1Mg alloy.

Electrochemical Noise Response of Cr2Nb Powders Applying Mechanical Alloying

Cr2Nb alloys are potential candidates for high-temperature structural materials. The influence of different mechanical alloying parameters (milling time) and sintering processes were studied. After mechanical alloying and observation by scanning electron microscope (SEM), nano powders were characterized and then sintered by spark plasma sintering (SPS). Electrochemical noise (EN) tests were also conducted in order to study the electrochemical behavior. From the current experimental results, it was revealed that ball milling times up to 20 h may explain the influence of Nb–Cr alloys and its association to the Laves phase and corrosion behavior. These insights aimed at improving the samples’ predicted behavior before spending time and resources at high-temperature industrial processes.

Preparation of nanostructural oxide dispersion strengthened (ODS) Mo alloy by mechanical alloying and spark plasma sintering, and its characterization

The nanostructural oxide dispersion strengthened (ODS) Mo alloy was successfully fabricated by mechanical alloying (MA) and spark plasma sintering (SPS). In this study, the MA and SPS conditions were systematically studied, and the characteristics of oxide particles were investigated. The results show that the MA process can refine the powder and promote the dissolution of interstitial atoms, but introduce the ZrO2 and excess O impurities. To recycle ZrO2 impurity as a source of active element Zr for alloy preparation, the content of Zr and O with milling time was quantitatively evaluated. In the SPS process, the precipitation of oxide particles retard the densification of as-MA Mo powders. Based on the calculated linear shrinkage, the densification behavior is controlled by sintering temperature, which is driven by grain boundary or dislocation climbing. A high relative density of 99.28% in ODS Mo alloy is achieved using the optimized MA (250 rpm/18 h) and SPS (1400 °C/5 min) parameters. Additionally, the ultrafine Mo grain structure (300 nm) and uniformly dispersed nanoscale Y-Zr-O oxide particles (20.32 nm) inside grains greatly improve the mechanical properties (569.63 ± 28.08 HV0.3) of ODS Mo alloys. Non-stoichiometric Y-Zr-O particles, with different Y/Zr ratios (Y/Zr <1), possess a special fluorite crystal structure.

Spark plasma sintering of Fe–Si–B–Cu–Nb / Finemet based alloys

The influence of mechanical alloying (MA) and spark plasma sintering (SPS) processing parameters on the microstructure, magnetic and mechanical properties of Finemet (Fe73.5Cu1Nb3Si13.5B9) type alloys was investigated. Finemet alloy powder was obtained via mechanical alloying of elemental powders for 30 h, 60 h, 90 h, and 120 h with ball to powder ratio (BPR) of 10:1 and 15:1. The milled powders were consolidated using the SPS process. The XRD patterns confirm the presence of the α-Fe3Si phase in all Finemet alloys, also broadening of the (110) peak of α-Fe3Si was observed with increasing milling time. The microhardness of Finemet alloys increases with increase in milling time primarily due to a decrease in grain size. All samples show good saturation magnetization (Ms), 120h sample exhibiting the highest Ms of 166 emu/g, however coercivity increases with increasing milling time. Additionally, α-Fe3Si crystal size decreases with increasing the BPR primarily due to higher impact energy.

Mapping of Wear Mechanism for Mechanical Alloyed Aluminum Carbon Nanotube Composites—An In Situ Analysis

AbstractThis research work investigates the root causes of wear on the tribo surface of mechanically alloyed Aluminum/CNT composite through a simulated in situ analysis. The wear maps are developed using the second-order polynomial regression equation for the Aluminum/CNT composite to discriminate the wear mechanisms at different levels of their influencing factors and milling parameters. As a result, the predominant wear mechanism is identified as surface fatigue for Aluminum/CNT composite under high loading dry sliding condition. This study also reveals the modes for eliminating the severe wear at the tribo-surfaces. Aluminum/CNT1 wt% composite fabricated with the mechanical alloying parameters above 6 h of milling time and above 5 rps of milling speed eliminates the delamination under low level of tribological parameters, and it achieves the minimal wear-rate of 30.5 × 10−6 g/m and coefficient of friction (CoF) of 0.346.

Influence of Mechanical Alloying and Sintering Temperature on the Microstructure and Mechanical Properties of a Ti-22Al-25Nb Alloy

In this research, a fine-grained Ti-22Al-25Nb (at.%) alloy was fabricated from the powders of Ti, Al and Nb by mechanical alloying (MA) and subsequent spark plasma sintering (SPS). The effects of MA and SPS parameters on the microstructure, micro-hardness and tribological properties of the sintered compacts were investigated and discussed. The single phase of (Ti, Al, Nb) bcc solid solution with the chemical composition of Ti-22Al-25Nb was produced by MA for 5-20 h and the rotation speed of 500 rpm. The mechanically alloyed powders for 5, 10, 15 and 20 h were subsequently consolidated by SPS at the temperature range of 1000-1300 °C for 60 min, respectively, followed by furnace cooling. The microstructures from the sintered compacts showed that the fine equiaxed B2 phase, the lamellar or equiaxed O phase, and the equiaxed α2 phase were present in all the sintered compacts. The highest micro-hardness value of 1840 HV0.3 and the smallest wear rate of 1.59 × 10−3 mm3/m were exhibited in the Ti-22Al-25Nb alloy sintered at 1100 °C/60 min/50 MPa.

Changes in the oxygen content, morphology, and microstructure of Mo-10Nb composite powders during mechanical alloying

The prefabrication of Mo-Nb composite powders is an effective way of improving the homogeneity of Mo-10Nb targets, which have broad application prospects in the photoelectric sensor industry. However, this aspect has been rarely addressed so far. Therefore, we prepared Mo-10Nb composite powders by mechanical alloying (MA), and investigated the effects of the experimental parameters such as the milling speed and duration on the particle morphology, size distribution, compositional homogeneity, crystallite size, inner strain, and oxygen content. High-quality Mo-10Nb composite powders with 3-μm spherical particles of narrow size distribution, homogeneous elemental distribution, and nanometric crystalline structure were obtained by implementing optimum MA parameters, viz., a milling speed of 250 rpm and duration of 36 h using an MITR QM-QX-4L omnidirectional ball mill. The mechanically alloyed Mo-10Nb composite powders were prone to oxidation when exposed to air, which led to a sharp increase in the oxygen content to ~5400 ppm. X-ray photoelectron spectroscopic analysis revealed the presence of Nb2O5, MoO2, and MoO3 on the surface of the Mo-10Nb particle. We believe that this study demonstrates an interesting strategy for the fabrication of high-quality Mo-10Nb targets.

Hydrogen generation from the reaction of Al-based composites activated by low-melting-point metals/oxides/salts with water

Aluminum metal needs to be activated to improve its hydrogen generation properties by using an inexpensive way for its wide adoption. Al-based composites activated by low-melting-point metals, oxides, and salts were prepared by high-energy ball milling and characterized using a range of instrumental analysis techniques. Uniform and orthogonal designs were chosen to optimize the components and mechanical alloying parameters of the Al-based composites, respectively, for improving their hydrogen generation properties and reducing cost. The results suggest that the Al-1.0 wt%Ga-1.5 wt%In-3.0 wt%SnCl2-1.0 wt%Bi2O3 composite prepared using the parameters A4B1C3D2 exhibited a hydrogen yield of 1172.3 mL g−1 and maximum hydrogen generation rate of 1030.5 mL min−1 g−1 at 25 °C and atmospheric pressure. The activation energy (Ea) of the hydrolysis reaction was calculated to be 20.0781 kJ mol−1. Moreover, according to the Tafel curves, the corrosion potential of Al-based composites in water becomes more negative compared with that of pure Al, which could improve its hydrogen generation properties. Therefore, this new material could be used as hydrogen sources for fuel cells.

Effect of mechanical alloying and spark plasma sintering on the microstructure and mechanical properties of ODS Eurofer

Oxide dispersion strengthened (ODS) Eurofer steel was prepared via mechanical alloying (MA) and spark plasma sintering (SPS). Different combinations of MA and SPS parameters were adopted in order to optimise the fabrication process. The experimental results show that the sample milled for 30 h, sintered at 1373 K at a pressure of 60 MPa has the highest density and microhardness among all the results obtained. As-produced ODS Eurofer shows a bimodal microstructure with homogeneously dispersed nanoscale Y2O3, that is beneficial for the mechanical properties. The yield and tensile strengths are higher while the elongation is lower in the top and bottom surfaces compared to the middle area of the sample. This is due to the presence of a larger number of M23C6 carbides, resulting from carbon diffusion from the mould material. As-produced samples were also subjected to a heat treatment. A good balance is achieved between the strength and ductility of the heat-treated material. Yielding properties comparable to hot isostatic pressing or hot extrusion as reported in the literature, the processing route presented by this study shows potential to produce high performance ODS Eurofer.

Synthesis of biodegradable Mg-Zn alloy by mechanical alloying: Statistical prediction of elastic modulus and mass loss using fractional factorial design

Abstract Biodegradable Mg-Zn alloy was synthesized using mechanical alloying where a statistical model was developed using fractional factorial design to predict elastic modulus and mass loss of the bulk alloy. The effects of mechanical alloying parameters (i.e., milling time, milling speed, ball-to-powder mass ratio and Zn content) and their interactions were investigated involving 4 numerical factors with 2 replicates, thus 16 runs of two-level fractional factorial design. Results of analysis of variance (ANOVA), regression analysis and R2 test indicated good accuracy of the model. The statistical model determined that the elastic modulus of biodegradable Mg-Zn alloy was between 40.18 and 47.88 GPa, which was improved and resembled that of natural bone (30–57 GPa). Corrosion resistance (mass loss of pure Mg, 33.74 mg) was enhanced with addition of 3%–10% Zn (between 9.32 and 15.38 mg). The most significant independent variable was Zn content, and only the interaction of milling time and ball-to-powder mass ratio was significant as P-value was less than 0.05. Interestingly, mechanical properties (represented by elastic modulus) and corrosion resistance (represented by mass loss) of biodegradable Mg-Zn alloy can be statistically predicted according to the developed models.

ВЛИЯНИЕ ПАРАМЕТРОВ МЕХАНИЧЕСКОГО ЛЕГИРОВАНИЯ НА МОРФОЛОГИЮ ЧАСТИЦ МЕТАЛЛОКЕРАМИЧЕСКОЙ ПОРОШКОВОЙ КОМПОЗИЦИИ ВЖ175+TiCN

ВЛИЯНИЕ ПАРАМЕТРОВ МЕХАНИЧЕСКОГО ЛЕГИРОВАНИЯ НА МОРФОЛОГИЮ ЧАСТИЦ МЕТАЛЛОКЕРАМИЧЕСКОЙ ПОРОШКОВОЙ КОМПОЗИЦИИ ВЖ175+TiCN

Influence of mechanical alloying on the microstructure and mechanical properties of powder metallurgy Ti2AlNb-based alloy

A fine grained Ti2AlNb-based alloy with a high strength was fabricated from elemental powders by mechanical alloying (MA) and subsequent spark plasma sintering (SPS). The effects of MA parameters on the microstructure and mechanical properties of the mechanically alloyed powder and sintered compacts were investigated. The single phase of (Ti, Al, Nb) bcc solid solution with a normal composition (mole fraction, %) of 53 Ti, 22 Al and 25 Nb was produced by MA for 40h/400rpm. The mechanically alloyed powder was subsequently synthesized by SPS at 1150°C/10min/35MPa followed by furnace cooling. The microstructure of the sintered alloy consisted of fine grained B2-matrix, ultrafine acicular O-phase inside B2-matrix, and ultrafine equiaxed α2-phases along the rim of B2-matrix. The yield strength and ultimate strength of the alloy sintered from the 40h mechanically alloyed powder were 1644MPa and 2542MPa in the compression test, respectively. Meanwhile, the strains to failure at room temperature and 650°C were 31.3% and 55.3%, respectively.

Optimization of mechanical alloying and spark-plasma sintering regimes to obtain ferrite–martensitic ODS steel

The results of structure investigation, distribution uniformity of dispersed particles of Y2O3, porosity and density of the ferritic/martensitic reactor steel EP-450 (0.12C–13Cr–2Mo–Nb–V–B, wt%) produced by spark-plasma sintering (SPS) are presented. More than 140 samples were produced using different combinations of mechanical alloying (time, speed of attritor rotation) and SPS parameters (temperature, speed of reaching preset temperature, pressure and time of exposure under pressure, concentration of strengthening particles). It is determined that the absence of strengthening Y2O3 nano-particles in local volumes of sintered specimens is connected with the imperfection of mechanical alloying, namely, the formation of agglomerates of matrix steel powder containing no oxide nano-particles. It has been determined that the time of mechanical alloying should not exceed 30h to provide minimum powder agglomeration, uniform distribution of Y2O3 particles in the powder mixture and minimum porosity of sintered samples. Spark-plasma sintering should be performed at the lowest possible temperature. As a result it was found that samples with 99% theoretical density can be obtained using the following optimized SPS-parameters: sintering temperature is 1098÷1163K; speed for reaching the preset temperature is >573K/min; load is 70÷80MPa; time of exposure under pressure – either without isothermal exposure, or exposure during ≥3min; optimum quantity of Y2O3 is 0.2÷0.5wt%.

A statistical prediction of density and hardness of biodegradable mechanically alloyed Mg–Zn alloy using fractional factorial design

This work aims to develop a statistical model that could be used to predict density and hardness properties of biodegradable mechanically alloyed magnesium–zinc alloy since both properties relies on densification of the powder during compaction and sintering. The effect of mechanical alloying parameters (i.e., milling time, milling speed, ball-to-powder weight ratio and percentage of zinc) and their interactions were investigated involving 4 numerical factors with 2 replicates, thus 16-run of two-level fractional factorial design. Results of analysis of variance (ANOVA), regression analysis and R-squared test indicated the good accuracy of the model. Density of sintered Mg–Zn alloy was between 1.80 and 1.99g/cm3 which closed to density of human bone. Hardness of pure Mg increased from 27HV to 54HV to 94HV with the addition of 3–10wt% Zn.

Role of mechanical alloying parameters on powder distribution of Al/Cu alloy and Al/Cu composite

The aim of the current study is to investigate the effect of milling time and speed on mixing properties of aluminium (Al)/copper (Cu) alloy and Al/Cu composite. Ethanol and argon gas were employed as process control agent and milling atmosphere. Mechanical alloying process by means of high-energy ball milling was performed to produce alloy and composite metal powder. This process proceeds through repeated deformation, cold welding and fracturing of powder particles mixture with a controlled fine microstructure. X-ray diffraction and particle size analyser confirmed particle size reduction of Al/Cu alloy with increasing milling time and speed. On the other hand, the addition of reinforcement particles was found to accelerate the milling process of Al/Cu composite. Scanning electron microscope micrographs revealed homogeneous distribution of powder mixture particles by mechanical alloying process at changing milling conditions.

Investigation of the Process of Mechanical Alloying of Iron by Austenite Forming Elements

In this study the effect of the treatment duration on the processes of phase formation and dissolution of alloying elements in the process of mechanical alloying (MA) of iron by austenite forming elements in the nitrogen-containing atmosphere was investigated. Investigating the influence of MA parameters on the phase composition of the alloy showed that the first alloying elements dissolved in the lattice of iron are nickel, chrome and manganese. According to experimental data, the dissolution proceeds through the formation of a layered composite.

Dissolution Of Alloying Elements And Phase Formation In Powder Materials Fe-18Cr-8Ni-12Mn-xN During Mechanichal Alloying

In this work, we investigated the effect of the treatment duration on the phase formation and dissolution of alloying elements in the process of mechanical alloying (MA) of iron with austenite forming elements in the nitrogen-containing atmosphere. The influence of MA parameters on the phase composition of the alloy showed the first of the alloying elements dissolved in the lattice of iron are nickel, then chrome and manganese. According to experimental data, the dissolution proceeds through the formation of a layered composite. Also the features of the nanocrystalline structure of powder materials Fe-18Cr-8Ni-12Mn-N, synthesized by mechanical alloying are presented. The nanocrystalline structure of these alloys consists of two structural components: grain-crystallites and grain boundary regions. Such type of structure corresponds to the Gleiter model. Dimensions of nanocrystals are in range from 6 to 20 nm.

Influence of Mechanical Alloying Parameters on Phase Formation in Al-Cu-Fe Powder

In the present study the e ect of mechanical alloying parameters on phase formation in Al62Cu25.5Fe12.5 (at.%) alloy was investigated. Mixtures of Al, Cu and Fe powder with di erent particles size were ball milled in Fritsch 5 Pulverisette planetary mill using tungsten carbide vials and balls. The milling was performed with the rotation speed 250 and 300 rpm up to 40 h. Stearic acid or hexane were used as process control agent (PCA). The microstructure of the powders prepared with di erent milling parameters was investigated using X-ray di raction and scanning electron microscopy. It was found that increase of the rotation speed as well as decrease of particle size of initial Al powder particles accelerates the formation of homogeneous microstructure of the powder. The mixture of icosahedral quasicrystal and β-Al(Cu, Fe) cubic phase has been obtained for the powders milled at 300 rpm up to 20 h. Prolonged milling time results in transformation to single ordered β phase.