Showing papers in "Materials Science and Technology in 2016"
TL;DR: In this article, the benefits of non-destructive testing, online monitoring and in situ machining are discussed, and strategies on how to manage residual stress, improve mechanical properties and eliminate defects such as porosity are suggested.
Abstract: Depositing large components (>10 kg) in titanium, aluminium, steel and other metals is possible using Wire + Arc Additive Manufacturing. This technology adopts arc welding tools and wire as feedstock for additive manufacturing purposes. High deposition rates, low material and equipment costs, and good structural integrity make Wire+Arc Additive Manufacturing a suitable candidate for replacing the current method of manufacturing from solid billets or large forgings, especially with regards to low and medium complexity parts. A variety of components have been successfully manufactured with this process, including Ti–6Al–4V spars and landing gear assemblies, aluminium wing ribs, steel wind tunnel models and cones. Strategies on how to manage residual stress, improve mechanical properties and eliminate defects such as porosity are suggested. Finally, the benefits of non-destructive testing, online monitoring and in situ machining are discussed.
1,051 citations
TL;DR: In this article, the effects of inherent surface roughness on the fatigue life of Ti-6Al-4V parts were investigated. And the results showed that the fatigue properties of these materials are dominated by roughness effects, and a simple model based on an equivalent initial flaw size was formulated.
Abstract: Additive manufacturing is increasingly considered for production of high quality, metallic, aerospace parts. Despite the high potential of this manufacturing process to reduce weight and lead time, the fundamental understanding of additive manufactured Ti–6Al–4V material is still at an early stage, especially in the area of fatigue and damage tolerance. This paper covers the effects of inherent surface roughness on the fatigue life. In the as built condition, metallic parts have a poor surface texture, which is generally removed in fatigue critical areas. It is shown that the fatigue properties of Ti–6Al–4V samples, produced by direct metal laser sintering and electron beam melting, are dominated by surface roughness effects. A simple model based on an equivalent initial flaw size is formulated.
249 citations
TL;DR: The research works of graphene-reinforced metal matrix composites are summarized in this paper, where the microstructure and mechanical properties, processing techniques, graphene dispersion, strengthening mechanisms, interfacial reactions between graphene and the metal matrix and future research works in this field are discussed.
Abstract: The research works of graphene-reinforced metal matrix composites will be summarised in this paper. Comparatively, much less research works have been undertaken in this field. Graphene has been thought to be an ideal reinforcement material for composites due to its unique two-dimensional structure and outstanding physical and mechanical properties. It is expected to yield structural materials with high specific strength or functional materials with exciting thermal and electrical characteristics. This paper will introduce all kinds of graphene-reinforced metal matrix composites that have been studied. The microstructure and mechanical properties, processing techniques, graphene dispersion, strengthening mechanisms, interfacial reactions between graphene and the metal matrix and future research works in this field will be discussed.
215 citations
TL;DR: In this paper, a concise overview of texture formation in alloys with cubic crystal structures, mainly steel and aluminium alloys, is given, where three key solid-state transformation processes are considered: allotropic phase transformations, plastic deformation and recrystallisation.
Abstract: The present paper gives a concise overview of a number of current issues in the literature on texture formation in alloys with cubic crystal structures, mainly steel and aluminium alloys. As crystallographic texture determines to a large extent the anisotropy of material properties, it is of paramount importance to understand and control the physical mechanisms by which the texture is formed in the subsequent stages of metals manufacturing processes. In the present overview three key solid-state transformation processes are considered: allotropic phase transformations, plastic deformation and recrystallisation. The intention is to highlight a number of key elements in the literature and some recent tendencies, which may provide some insight to scientists and engineers dealing with texture issues in daily practice.
167 citations
TL;DR: In this article, a review of white structure flaking (WSF) in gearbox bearing raceways is presented, which can occur in as little as 6-24 months of operation by the formation of axial cracks and white etching cracks.
Abstract: The actual service life of wind turbine gearboxes is often well below the desired 20 years. One of the prevalent failure modes in gearbox bearing raceways is white structure flaking (WSF) in as little as 6–24 months of operation by the formation of axial cracks and white etching cracks (WECs) with associated microstructural change called white etching areas (WEAs). Despite these failures having been observed for two decades in various industries, the drivers and mechanisms for their formation are still highly contested. Discussed in this review are methods for searching and analysing WECs, mechanisms for WEA microstructural change, WEC initiation and propagation theories, WSF formation drivers and finally technologies and processes offering resistance to WSF. This updated review serves as a recap, comprehensive update on findings, current focus areas and remaining challenges.This paper is part of a Themed Issue on Recent developments in bearing steels.
156 citations
TL;DR: In this paper, high-pressure rolling was applied to each layer of a linear Ti-6Al-4V wire + arc additive manufacturing component in between deposition passes, and the results were validated with neutron diffraction measurements, which were in good agreement away from the baseplate.
Abstract: Wire + arc additive manufacturing components contain significant residual stresses, which manifest in distortion. High-pressure rolling was applied to each layer of a linear Ti–6Al–4V wire + arc additive manufacturing component in between deposition passes. In rolled specimens, out-of-plane distortion was more than halved; a change in the deposits' geometry due to plastic deformation was observed and process repeatability was increased. The Contour method of residual stresses measurements showed that although the specimens still exhibited tensile stresses (up to 500 MPa), their magnitude was reduced by 60%, particularly at the interface between deposit and substrate. The results were validated with neutron diffraction measurements, which were in good agreement away from the baseplate.This paper is part of a Themed Issue on Measurement, modelling and mitigation of residual stress.
148 citations
TL;DR: In this article, a comparative study is presented showing the utility of the energy density parameter in process optimisation for γ and γ′/γ″ strengthened Ni-based superalloys.
Abstract: The main challenge associated with the application of selective laser melting (SLM) to Ni based superalloys is the performance of process optimisation to maximise the mechanical properties. The energy density parameter has typically been used as a semiquantitative approach to identify the energy threshold beyond which the material achieves virtually full consolidation. Nonetheless, some Ni superalloys are susceptible to crack formation during SLM, which cannot be avoided via process optimisation. In the present report, a comparative study is presented showing the utility of the energy density parameter in process optimisation for γ′ and γ′/γ″ strengthened Ni based superalloys. For both classes, it was found that the build density increases [i.e. void area (%) decreases] with the increase in the energy density. Nonetheless, no direct correlation can be found between the energy density parameter and the cracking density.
147 citations
TL;DR: In this paper, the material aspects of two different nanoparticles, nanosilica and montmorillonite nanoclay, the complications that arise from their addition to cement pastes and ways to mitigate these limitations are discussed.
Abstract: The need to produce sustainable cements has driven research towards nanotechnology. The main cement hydration product, calcium silicate hydrate, is nanosized; hence, the addition of nanoparticles to blended Portland cement formulations can remarkably modify mechanical strength, porosity and durability. The present paper discusses the material aspects of two different nanoparticles, nanosilica and montmorillonite nanoclay, the complications that arise from their addition to cement pastes and ways to mitigate these limitations. It is deduced that nanosilica solids in blended cement pastes should be limited to 0.5%, whereas nanoclay solids to almost 1 mass-% binder. Competitive reactivity of nanoparticles with other constituents is expected, and the possible pozzolanic activity is critically addressed. Notwithstanding progress made, there are significant potentials related to inorganic nanoclays.
74 citations
TL;DR: In this article, a novel Cr containing Co-Al-W base superalloys were studied by atom probe tomography and neutron diffraction, and they were found to predominantly partition to the γ matrix and decrease partitioning of W to γ′.
Abstract: Novel Cr containing Co-Al-W base superalloys were studied by atom probe tomography and neutron diffraction. Cr is found to predominantly partition to the γ matrix and decrease partitioning of W to γ′. Furthermore, Cr significantly enhances the γ′ volume fraction, decreases the γ/γ′ lattice misfit and deteriorates the creep resistance. Addition of Ni to the Cr containing alloys affects partitioning of W and Al, further decreases the lattice misfit and results in the formation of irregularly shaped precipitates. Al, W and Cr tend to occupy the ‘B'sublattice in the γ′-A3B phase (L12 type), while Co and Ni reside in the ‘A' sublattice.
70 citations
TL;DR: In this article, the influence of Z phase precipitation upon long term creep strength is assessed from several different 9-12-wt-%Cr steel grades and alloy design philosophies, including thermodynamic modelling, crystal structure, nucleation process and precipitation rate as a function of chemical composition.
Abstract: For high temperature applications, 9–12 wt-%Cr steels in fossil fired power plants rely upon precipitate strengthening from (V,Nb)N MX nitrides for long term creep strength. During prolonged exposure at service temperature, another nitride precipitates: Cr(V,Nb)N Z phase. The Z phases lowly replace MX, eventually causing a breakdown in creep strength. The present paper reviews the Z phase and its behaviour in 9–12 wt-%Cr steels including thermodynamic modelling, crystal structure, nucleation process and precipitation rate as a function of chemical composition. The influence of Z phase precipitation upon long term creep strength is assessed from several different 9–12wt-%Cr steel grades and alloy design philosophies.
54 citations
TL;DR: In this paper, a numerical model based on energy approach has been proposed to predict the effective elastic modulus of fabricated lattice samples, which can be used to determine the parameters of lattice structures fabricated by binder jetting process for desired mechanical properties.
Abstract: This study mainly evaluates the elastic modulus of 316 stainless steel lattice structures fabricated via binder jetting process. In this present research, both solid and lattice samples are designed and fabricated by binder jetting process for two different types of mechanical tests. Besides experimental study, a numerical model based on energy approach has been proposed to predict the effective elastic modulus of fabricated lattice samples. By comparing the calculated results of the proposed numerical model with the experimental results, the established model is proved to be validated. This numerical model can be used to determine the parameters of lattice structures fabricated by binder jetting process for desired mechanical properties. At the end, both advantages and disadvantages of the lattice structures fabricated by binder jetting process are analysed. Based on this analysis, the potential application and future research work are pointed out.
TL;DR: The available glass forming ability criteria have been examined by classifying them into four basic categories depending on critical temperatures, thermodynamic quantities, topological and kinetic aspects of glass forming alloys as discussed by the authors.
Abstract: The available glass forming ability criteria have been examined by classifying them into four basic categories depending on critical temperatures, thermodynamic quantities, topological and kinetic aspects of glass forming alloys. A large number of glass forming alloys of widely varying natures and origin have been analysed with their experimentally measured properties to assess their glass forming ability. A novel approach using kinetic viscosity of glass forming alloys obtained by the Vogel–Fulcher–Tamman equation and the critical cooling rate calculated from the TTT diagram is demonstrated as an excellent universal glass forming ability criterion. Moreover, thermodynamic and topological modelling results through computation of a novel PHSS parameter for various alloy compositions spanning different alloy systems have rendered qualitative guidelines on propensity for glass formation in multicomponent alloy systems. Besides, the importance of kinetic interpretation of PHSS range observed for glass forming...
TL;DR: In this paper, the effects of boron addition on the microstructure, hardness and corrosion resistance of high-entropy alloy coatings were studied. And the results showed that the borides changed from orthorhombic (Cr, Fe) to tetragonal (Fe, Cr)2B, which deteriorated the corrosion resistance.
Abstract: FeCrNiCoBx high-entropy alloy coatings were prepared by laser cladding, and the effects of boron addition on the microstructure, hardness and corrosion resistance of the coatings were studied. Results showed that the coatings comprised a simple FCC solid solution with boride precipitation. When 0.5 ≤ x ≤ 1.0, (Cr, Fe)2B with an orthorhombic structure was found in the coatings, and the hardness and corrosion resistance of the coatings were enhanced by increasing boron content. As x approached 1.25, the borides changed from orthorhombic (Cr, Fe)2B to tetragonal (Fe, Cr)2B, which deteriorated the corrosion resistance of the coatings. Stacking faults found in (Cr, Fe)2B may be caused by the phase transformation of borides.
TL;DR: In this paper, depth-dependent hardness variation of dimethylamine borane-reduced electroless Ni-5'wt-%B deposits has been examined using the nanoindentation technique.
Abstract: Depth-dependent hardness variation of dimethylamine borane-reduced electroless Ni–5 wt-%B deposits has been examined using the nanoindentation technique. The deposits were characterised using ICP-OES, FESEM, XRD and DSC for evaluating the composition, morphology, structure and phase transformation behaviour, respectively. Coatings were also analysed for hardness and wear resistance. The surface of the as-plated deposit exhibits a typical nodular morphology. DSC traces show the presence of a single exothermic peak at 313°C conforming to its phase transformation. X-ray diffraction pattern of as-prepared deposit contains a mixture of amorphous and sharp microcrystalline nickel peaks. Heat-treated coating exhibits improved hardness and wear resistance. Depth-dependent nanohardness profile of as-deposited film neither obeys Nix–Gao nor the Lam–Chong model of indentation.
TL;DR: The stacking fault energy (SFE) can play a key role in the deformation mechanism (e.g. transformation-induced plasticity and twinning-induced plasticity) of austenitic steels.
Abstract: The stacking fault energy (SFE) can play a key role in the deformation mechanism (e.g. transformation-induced plasticity and twinning-induced plasticity) of austenitic steels. Therefore, tremendous efforts have been devoted to exploring the evaluation methods and controlling parameters (e.g. alloying elements and temperature) that determine the SFE and its relationship to mechanical twinning. We provide here a summary of recent progress in studies of the SFE of austenite and of unsolved issues that may stimulate further investigation.
TL;DR: In this article, a complementary use of SEM and TEM with the focus on the use of orientation contrast imaging and electron backscatter diffraction (EBSD) was used for the first time to give detailed insight into the microstructure of WEA.
Abstract: In the present work, crack networks with white etching areas (WEAs) in cross-sections of bearings were investigated by a complementary use of SEM and TEM with the focus on the use of orientation contrast imaging and electron backscatter diffraction (EBSD). Orientation contrast imaging was used for the first time to give detailed insight into the microstructure of WEA. A significant difference between Nital-etched and polished WEA samples was observed. It was revealed that WEAs are composed of different areas with varying grain sizes. As a result of secondary transformation, needle-shaped grains were observed within WEAs. Using EBSD analysis, evidence was obtained that WEA formation and accompanying crack growth are without relation microstructural features. In addition, an inhomogeneous chemical structure of WEA as a result of carbide dissolution is revealed by analytical investigations.
TL;DR: In this paper, the microstructures of high entropy alloys of the system CoCrCuFexNi and CoCrcuFeNix (where x indicates the molar ratio, which, where not specified, is 1) have been investigated.
Abstract: The microstructures of high entropy alloys of the system CoCrCuFexNi and CoCrCuFeNix (where x indicates the molar ratio, which, where not specified, is 1) have been investigated. Many Cu rich spheres were evident in the microstructure of CoCrCuFe0.5Ni and CoCrCuFeNi0.5 alloys, which indicates that liquid phase separation had occurred before solidification. During liquid phase separation, the original liquids separated into two liquids: Cu rich and Cu depleted. In contrast, in other alloys (x = 1.0, 1.5 and 2.0), typical dendritic and interdendritic structures are obtained. Cu and/or Cr rich precipitates, with various morphologies, can be seen in the interdendritic region. Additionally, Cu rich nanoparticles and Cr rich bird shaped structures can be observed in the Cu rich spheres. Sluggish cooperative diffusion causes the element segregation and formation of nanoprecipitates in the microstructures. The calculated positive mixing enthalpies of CoCrCuFe0.5Ni and CoCrCuFeNi0.5 alloys are likely reasons for t...
TL;DR: In this paper, the authors obtained different morphology and size of epsilon carbides (ϵ-carbides) via low temperature tempering of 0.32 wt-% C low alloy wear resistance steel.
Abstract: In this study, we obtained different morphology and size of epsilon carbides (ϵ-carbides) via low temperature tempering of 0.32 wt-% C low alloy wear resistance steel. The objective is to elucidate the determining role of size and morphology of carbides on mechanical properties and three-body impact wear resistance. The formation of small needle-like ϵ-carbides was responsible for increase in yield strength, low temperature impact toughness and three-body impact wear resistance. However, when the ϵ-carbides were large and rod-like, hardness, toughness and three-body impact wear resistance were significantly reduced. The wear mechanism of steel containing needle-like ϵ-carbides primarily involved plastic deformation associated with fatigue and small degree of abrasive wear and furrow, while steels containing rod-like ϵ-carbides were predominantly characterised by furrow.
TL;DR: In this article, the effect of polarisation fields on the band structure of heterostructure quantum wells, known as the quantum confined stark effect, and its implications for the efficiency and spectral stability of LEDs have also been reviewed.
Abstract: III-Nitrides are materials that have revolutionised the lighting industry allowing for the development of high brightness and efficiency white light emitting diodes (LEDs), enabling cost and energy savings at an unprecedented scale. However, there remain several obstacles to the further enhancement of the efficiency of LEDs, particularly for emission at longer wavelengths. The existence of polarisation fields as an inherent property of wurtzite III-nitride materials severely hampers LED performance. The origin of these fields due to the deviation from an ideal tetrahedral bonding structure and their relation to strain has been addressed in this review. The effect of the polarisation fields on the band structure of heterostructure quantum wells, known as the quantum confined stark effect, and its implications for the efficiency and spectral stability of LEDs have also been reviewed. Finally, the effectiveness and viability of several proposed methods of mitigating the harmful effects of the polarisation fi...
TL;DR: In this article, a review of the chemical preparation methods, different modification methods and various applications of the Fe3O4-based MPNPs are introduced, including the application in wastewater treatment and biological field such as magnetic resonance imaging contrast agents, hyperthermia therapy and protein separation.
Abstract: Fe3O4 based magnetic polymer nanoparticles (MPNPs) are densely studied for several decades These Fe3O4 based MPNPs can be used in wastewater treatment and biological field such as magnetic resonance imaging contrast agents, hyperthermia therapy and protein separation The Fe3O4 based MPNPs are attractive because they combine the advantages of magnetism and polymers together In order to obtain the practical application in the above mentioned areas, the bare Fe3O4 needs to be functionalised with different kinds of molecules like organic small molecules and polymers and some inorganic molecules like silica, metals and carbon In this review, the chemical preparation methods, different modification methods and various applications of the Fe3O4 based MPNPs are introduced
TL;DR: In this paper, the effect of retained austenite on wear resistance was investigated in nanostructured super bainitic and quenching-partitioning (Q&P) martensitic steels.
Abstract: Nanostructured super bainitic and quenching–partitioning (Q&P) martensitic steels with a significant amount of retained austenite obtained by low temperature bainitic transformation and Q&P respectively were studied to explore the effect of retained austenite on stirring wear resistance. The results suggest that the Q&P martensitic steel significantly enhanced the hardness of the worn surface (from 674 to 762 HV1) and increased the thickness of the deformed layer (∼3.3 μm), compared to the nanostructured bainitic steel. The underlying reason is that the Q&P martensitic steel has a higher stability of retained austenite thereby providing a superior transformation induced plasticity effect to increase surface hardness and reduce wear rate during the wear process.
TL;DR: In this article, a light weight magnesium composite foams are synthesized by adding of fly ash cenosphere particles (waste from coal-fired power plants) in biocompatible pure magnesium using solidification-based disintegrated melt deposition technique.
Abstract: Significantly light weight magnesium composite foams are synthesised by addition of fly ash cenosphere particles (waste from coal-fired power plants) in biocompatible pure magnesium using solidification-based disintegrated melt deposition technique. The density of the composite foams synthesised in this study approaches that of plastics- and polymer-based composites. Microstructure development of Mg/cenosphere composite foams was favourable as they exhibited better dimensional stability (reduced coefficient of thermal expansion) and remarkable improvements in tensile strengths, compressive strengths, compressive total strain and microhardness. The present study highlights the processing, microstructure and mechanical properties of Mg/cenosphere composite foams which hold great potential as light weight metal-based green materials for diverse weight critical applications spanning from engineering to biomedical sector.
TL;DR: In this paper, the authors present the characteristics of the performance of austenitic steel Super 304H and HR3C used for construction of boilers with supercritical and ultra-supercritical steam parameters.
Abstract: This paper presents the characteristics of the performance of austenitic steel Super 304H and HR3C used for construction of boilers with supercritical and ultra-supercritical steam parameters. Characteristic microstructure images of the examined steels in the as received condition observed with the scanning electron microscope are shown. The method for strength assessment based on abridged creep tests carried out at a temperature higher than the design one is presented on the example of examined steels. It has been demonstrated that the obtained results do not deviate from the values of creep strength determined in long-term creep tests. The maximum difference is ± 20%, which is in compliance with the acceptable scatter band. The presented methodology can be used for verification of creep strength.
TL;DR: In this article, a laser-engineered net shaping technology was successfully used to fabricate 316L stainless steel bulk specimens using unidirectional scanning path and weaving scanning path.
Abstract: In the present study, laser engineered net shaping technology was successfully utilised to fabricate 316L stainless steel bulk specimens using unidirectional scanning path and weaving scanning path. Influence of scanning path and post-heat treatment on microstructural and mechanical properties of the as-deposited builds has been investigated. The results show that scanning paths have a significant impact on the grain morphology evolution. Consequently, the as-made samples by different scanning strategies show a great difference in the mechanical properties. Furthermore, the experimental results also demonstrate that post-heat treatment is an essential step in further optimising microstructure and improving mechanical properties.
TL;DR: In this article, a link between three-dimensional crack tomography, crack propagation rate and oxygen-related attack is established, and quantitative models which include the interaction between fatigue-creep-oxygen attack need further development.
Abstract: Ni-based superalloys in turbine disc applications face increasing susceptibility to oxygen-assisted fatigue crack propagation due to increased turbine entry temperatures. The continued lack of understanding of the interplay between the factors operating during oxygen-assisted fatigue crack propagation limits: (1) development of lifing methodologies to accurately predict the fatigue performance of disc alloys/components and (2) associated disc alloy developments. An underpinning requirement to better understand the role of oxygen is to characterise the process of oxygen diffusion in the localised stress/strain state at the crack tip, which is related closely to microstructural features. The link between three-dimensional crack tomography, crack propagation rate and oxygen-related attack needs to be established. Quantitative models which include the interaction between fatigue–creep–oxygen attack need further development.
TL;DR: In this article, the interaction between spinel solids and Cu-droplets is investigated in an industrially relevant slag system (PbO-CaO-SiO2-Cu2O-Al2O3-FeO-ZnO) using two complementary experimental set-ups.
Abstract: Cu-droplet losses in slags are an important problem in Cu-industry, limiting the metal recovery. An important cause responsible for the entrainment of copper droplet losses in slags is their sticking behaviour to spinel solids. In the present study, the interaction between spinel solids and Cu-droplets is investigated in an industrially relevant slag system (PbO–CaO–SiO2–Cu2O–Al2O3–FeO–ZnO) using two complementary experimental set-ups. Firstly the influence of the sedimentation time is studied and secondly the presence of entrained (sticking) droplets is studied as a function of height in the slag layer. Based on the experimental results, a mechanism that explains the sticking Cu-droplets is proposed. Finally, a model describing the sedimentation of sticking and non-sticking droplets is formulated based on the experimental data.
TL;DR: In this article, the influence of hydrogen on the mechanical properties of generic lab-cast Fe-C bainitic alloys is studied by tensile tests on notched samples.
Abstract: The influence of hydrogen on the mechanical properties of generic lab-cast Fe–C bainitic alloys is studied by tensile tests on notched samples. The bainitic microstructure is induced in a 0.2% C and 0.4% C Fe–C alloy by an appropriate heat treatment. The hydrogen embrittlement susceptibility is evaluated by mechanical tests on both in situ hydrogen pre-charged and uncharged specimens. The observed ductility loss of the materials is correlated with the present amount of hydrogen and the hydrogen diffusion coefficient. In addition to the correlation between the amount of hydrogen and the hydrogen-induced ductility loss, the hydrogen diffusion during the tensile test, quantified by the hydrogen diffusion distance during the test, appears to be of major importance as well.
TL;DR: In this article, a critical assessment is performed concerning the most important influencing parameters and processing routes for bainitic steels, and cooling concepts are discussed regarding their optimal chemical composition, achievement of homogeneous microstructure and a low sensitivity to processing parameters.
Abstract: Recent developments of direct heat-treated steels for high strength forgings have led to some new steel grades with excellent service properties. Quenched and tempered steels are nowadays more and more replaced by precipitation hardened ferritic–pearlitic steels and by bainitic steels. Based on the experience on upper, lower and carbide-free bainite, a critical assessment is performed concerning the most important influencing parameters and processing routes. Steel designs and cooling concepts are discussed regarding their optimal chemical composition, achievement of a homogeneous microstructure and a low sensitivity to processing parameters. Some controversial aspects are illustrated and further need for research work is highlighted.
TL;DR: In this paper, a review of the selective laser sintering process and its research progress with the use of metallic powders is presented, where the main focus of whole available research progress is to produce complex shape solid model/parts using different metallic materials having the desired mechanical as well as dimensional properties.
Abstract: Laser sintering is a newly well established additive manufacturing technique, which has higher capabilities to produce complex shapes models/parts in a short time period. In this technique, a solid model is directly produced according to computer aided design model, by fusing two adjacent layers together, with the interaction of laser light. These parts are widely used in industries like aerospace and automobile and for medical applications as well. This paper reviews the selective laser sintering process and its research progress with the use of metallic powders. The main focus of whole available research progress is to produce complex shape solid model/parts using different metallic materials having the desired mechanical as well as dimensional properties.
TL;DR: In this article, a new empirical rule to form single phase solid solution structured high entropy alloys was proposed by integrating three dependent parameters, i.e., atomic size difference δ, mixing enthalpy ΔHmix and valence electron concentration VEC.
Abstract: A new empirical rule to form single phase solid solution structured high entropy alloys was proposed by integrating three dependent parameters, i.e. atomic size difference δ, mixing enthalpy ΔHmix and valence electron concentration VEC. It was found that the single phase face centred cubic solid solution will form if δ 8, while the single phase body centred cubic solid solution will form in the case of δ < 4.27%, − 7.27 kJ mol− 1 < ΔHmix < 4 kJ mol− 1 and VEC < 6.87. This empirical rule was verified by typical high entropy alloys that have been reported.