Crystallography, Cristallographie cristallogenèse, Chemical industry parachemical industry, Industrie chimique et parachimique, Metallurgy, welding, Métallurgie, soudage, Condensed state physics, Physique de l'état condensé, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Métallurgie des poudres. Matériaux composites, Powder metallurgy. Composite materials, Technologie, Technology, Aluminium alliage, Aluminium alloy, Aluminio aleación, Aluminiumlegierung, Assemblage, Joining, Ensamble, Verbinden, Bille, Ball, Bola, Kugel, Chaleur réaction, Heat of reaction, Calor reacción, Reaktionswaerme, Commande processus, Process control, Control proceso, Prozesssteuerung, Composé intermétallique, Intermetallic compound, Compuesto intermetálico, Intermetallische Verbindung, Etat fondu, Molten state, Estado fundido, Etude expérimentale, Experimental study, Estudio experimental, Experimentelle Untersuchung, Microscopie électronique balayage, Scanning electron microscopy, Microscopía electrónica barrido, Rasterelektronenmikroskopie, Nickel alliage, Nickel alloy, Níquel aleación, Nickellegierung, Prototypage rapide, Rapid prototyping, Prototipificación rápida, Synthèse combustion, Combustion synthesis, Al Ni, Alliage AlNi, Intermetallics: Nickel-aluminide bead, Microjoining, and Reactive rapid prototyping

Reactive rapid prototyping is a new freeform fabrication method for intermetallics which is a combined process of the combustion synthesis and rapid prototyping. Nickel-aluminide objects are built through microjoining of small nickel-aluminide beads which are formed by ejecting fused aluminum droplets onto a nickel powder bed. In order to obtain fine objects, it is necessary to minimize the bead size and control the product's composition. Nickel addition to aluminum was effective to reduce the reaction heat for a decrease in a bead size. Increasing temperature of aluminum droplets to 1000 °C tended to form beads being rich in NiAl phase. A newly developed nozzle with double orifices could eject aluminum droplets uniformly and continuously, resulting in forming a thin line of nickel-aluminide with ∼ 0.7 mm in width and a simple 2D structure with a few pores and cracks.

Crystallography, Cristallographie cristallogenèse, Chemical industry parachemical industry, Industrie chimique et parachimique, Metallurgy, welding, Métallurgie, soudage, Condensed state physics, Physique de l'état condensé, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Métallurgie des poudres. Matériaux composites, Powder metallurgy. Composite materials, Technologie, Technology, Métal transition alliage, Transition metal alloy, Metal transición aleación, Uebergangsmetallegierung, Alliage binaire, Binary alloy, Aleación binaria, Aluminium alliage, Aluminium alloy, Aluminio aleación, Aluminiumlegierung, Assistance ordinateur, Computer aid, Asistencia ordenador, Rechnerunterstuetzung, Commande processus, Process control, Control proceso, Prozesssteuerung, Composé intermétallique, Intermetallic compound, Compuesto intermetálico, Intermetallische Verbindung, Etude expérimentale, Experimental study, Estudio experimental, Experimentelle Untersuchung, Microscopie électronique balayage, Scanning electron microscopy, Microscopía electrónica barrido, Rasterelektronenmikroskopie, Nickel alliage, Nickel alloy, Níquel aleación, Nickellegierung, Prototypage rapide, Rapid prototyping, Prototipificación rápida, Synthèse combustion, Combustion synthesis, Al Ni, and Alliage AlNi

A new freeform fabrication method for intermetallics named Reactive Rapid Prototyping (RRP), which combines combustion synthesis and rapid prototyping, has been developed. Small droplets of molten aluminum ejected onto the nickel powder bed on the moving x-y-z stage form and simultaneously join hot nickel aluminide beads eventually building up the 3-D object. The RRP is systematically controlled by computer. The process control was investigated because the formation and joining of beads are influenced by temperature and volume of aluminum droplets, time and space intervals of their ejection, thickness of the nickel powder bed, and reaction control agents. The addition of fine alumina particles to the nickel powder bed effectively controlled the spreading of the bead formation. Joinings between adjacent beads and between layers were successfully performed without cracks and pores. The boundary region between layers was composed of NiAl phase, but the interior in each layer shifted from the stoichiometric composition.

Crystallography, Cristallographie cristallogenèse, Chemical industry parachemical industry, Industrie chimique et parachimique, Metallurgy, welding, Métallurgie, soudage, Condensed state physics, Physique de l'état condensé, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Métallurgie des poudres. Matériaux composites, Powder metallurgy. Composite materials, Technologie, Technology, Analyse thermique, Thermal analysis, Análisis térmico, Thermische Analyse, Diffraction RX, X ray diffraction, Difracción RX, Roentgenbeugung, Dureté, Hardness, Dureza, Haerte, Etude expérimentale, Experimental study, Estudio experimental, Experimentelle Untersuchung, Fabrication, Manufacturing, Fabricación, Fertigung, Formage, Forming, Conformado, Umformen, Matériau gradient fonctionnel, Functionnally graded material, Material gradiente functional, Microstructure, Microestructura, Mikrogefuege, Nickel, Niquel, Propriété mécanique, Mechanical properties, Propiedad mecánica, Prototypage rapide, Rapid prototyping, Prototipificación rápida, Résistance flexion, Bending strength, Resistencia flexión, Biegefestigkeit, SEM, Synthèse combustion, Combustion synthesis, Titane carbure, Titanium carbide, Titanio carburo, and Titancarbid

TiC-Ni functionally gradient materials (FGM) parts were fabricated by laminated object manufacturing (LOM), one of rapid prototyping (RP) techniques and combustion synthesis technique. The microstructure and phases of TiC-Ni FGM were analyzed with SEM and XRD. TiC-Ni FGM had anisotropic mechanical properties. It was stronger in the direction parallel to the thickness than in the direction perpendicular to the thickness. The maximum strength was 950 MPa in the TiC-20wt.%Ni region. The hardness of TiC-Ni FGM was larger than HRA 84 and the density was larger than 5.2 g cm 3. When the content of Ni raised the density increased, then there was the largest relative density in the TiC-20wt.%Ni region.

Mechanical engineering, Génie mécanique, Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Métallurgie des poudres. Matériaux composites, Powder metallurgy. Composite materials, Technologie, Technology, Dépôt, Deposition, Depósito, Beschichten, Modélisation, Modeling, Modelización, Particule, Particle, Partícula, Polymérisation, Polymerization, Polimerización, Procédé fabrication, Manufacturing process, Procedimiento fabricación, Fertigungsverfahren, Prototype, Prototipo, Prototyp, Solidification, Solidificación, Erstarren, Technologie industrielle, Industrial technology, Tecnología industrial, Frittage laser spécifique, and Stéréolithographie

Crystallography, Cristallographie cristallogenèse, Chemical industry parachemical industry, Industrie chimique et parachimique, Metallurgy, welding, Métallurgie, soudage, Condensed state physics, Physique de l'état condensé, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Métallurgie des poudres. Matériaux composites, Powder metallurgy. Composite materials, Technologie, Technology, Propriétés mécaniques. Rhéologie. Mécanique de la rupture. Tribologie, Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology, Elasticité. Plasticité, Elasticity. Plasticity, Analyse structurale, Structural analysis, Análisis estructural, Essai compression, Compression test, Ensayo compresión, Druckversuch, Essai flexion, Bending test, Ensayo flexion, Etat fondu, Molten state, Estado fundido, Faisceau électronique, Electron beam, Haz electrónico, Elektronenstrahl, Fusion, Melting, Fusión, Schmelzen, Modèle stochastique, Stochastic model, Modelo estocástico, Modélisation, Modeling, Modelización, Mousse métallique, Metal foam, Espuma metálica, Metallschaum, Méthode élément fini, Finite element method, Método elemento finito, Finite Element Methode, Structure cellulaire, Cell structure, Estructura celular, Zellengefuege, Titane alliage, Titanium alloy, Titanio aleación, Titanlegierung, and Non-stochastic foams,Repeating open cell structures,Ti-6Al-4V,Direct metal fabrication,Layered manufacturing,Rapid prototyping

This paper addresses foams which are known as non-stochastic foams, lattice structures, or repeating open cell structure foams. The paper reports on preliminary research involving the design and fabrication of non-stochastic Ti-6Al-4V alloy structures using the electron beam melting (EBM) process. Non-stochastic structures of different cell sizes and densities were investigated. The structures were tested in compression and bending, and the results were compared to results from finite element analysis simulations. It was shown that the build angle and the build orientation affect the properties of the lattice structures. The average compressive strength of the lattice structures with a 10% relative density was 10 MPa, the flexural modulus was 200 MPa and the strength to density ration was 17. All the specimens were fabricated on the EBM A2 machine using a melt speed of 180 mm/s and a beam current of 2 mA. Future applications and FEA modeling were discussed in the paper.

Crystallography, Cristallographie cristallogenèse, Chemical industry parachemical industry, Industrie chimique et parachimique, Metallurgy, welding, Métallurgie, soudage, Condensed state physics, Physique de l'état condensé, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Domaines interdisciplinaires: science des materiaux; rheologie, Cross-disciplinary physics: materials science; rheology, Science des matériaux, Materials science, Diagrammes de phases et microstructures développées par solidification et par transformations de phases solide-solide, Phase diagrams and microstructures developed by solidification and solid-solid phase transformations, Solidification, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Métallurgie des poudres. Matériaux composites, Powder metallurgy. Composite materials, Technologie, Technology, Cuivre alliage, Copper alloys, Cuivre, Copper, Densification, Distribution concentration, Concentration distribution, Distribución concentración, Konzentrationsverteilung, Effet Marangoni, Marangoni effect, Etat fondu, Melts, Frittage, Sintering, Gradient température, Temperature gradients, Interface liquide solide, Liquid solid interface, Interfase líquido sólido, Grenzschicht fluessig fest, Matériau composite, Composite materials, Microstructure, Métal transition alliage, Transition element alloys, Métal transition, Transition elements, Métallurgie poudre, Powder metallurgy, Solidification rapide, Rapid solidification, Tungstène alliage, Tungsten alloys, Viscosité, Viscosity, Direct metal laser sintering (DMLS), Marangoni flow, Rapid prototyping (RP), and W-Cu

The direct metal laser sintering (DMLS) was used to consolidate a composite powder system consisting of submicron W-Cu powder and micron Cu powder. The influence of Cu-liquid content on densification response of direct laser sintered W-Cu components was investigated. It was found that a proper increase of Cu elemental fraction to 60 wt.% yielded a high densification of 94.8% theoretical density, due to a favorable viscosity of liquid-solid mixture and the resultant sufficient rearrangement of W particles. However, a further increase in Cu content deteriorated laser sintered density, because of balling effect. The effect of Cu-liquid content on microstructural features of laser-processed components was also studied. It showed that at a suitable Cu elemental content of 60 wt.%, a series of regularly shaped W-rim/Cu-core structures were formed after laser sintering. The metallurgical mechanisms for the formation of such a novel structure were proposed. It shows that the combined action of the thermal Marangoni flow and the solutal one, which are induced by temperature gradient and concentration differences at solid-liquid interfaces, accounts for the formation of the W-rim. The particle pushing effect during rapid solidification of Cu melt prevents the W-rim from merging and, thus, remains the Cu-core after solidification.

Crystallography, Cristallographie cristallogenèse, Chemical industry parachemical industry, Industrie chimique et parachimique, Metallurgy, welding, Métallurgie, soudage, Condensed state physics, Physique de l'état condensé, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Métallurgie des poudres. Matériaux composites, Powder metallurgy. Composite materials, Technologie, Technology, Contrôle, Analysing. Testing. Standards, Analyse des contraintes, Stress analysis, Acier inoxydable 316, Stainless steel-316, Contrainte axiale, Axial stress, Tensión axial, Contrainte résiduelle, Residual stress, Tensión residual, Eigenspannung, Diffraction neutron, Neutron diffraction, Difracción neutrónica, Neutronenbeugung, Fusion laser, Laser fusion, Fusión láser, Inconel 718, Mesure contrainte, Stress measurement, Procédé fabrication, Manufacturing process, Procedimiento fabricación, Fertigungsverfahren, Prototypage rapide, Rapid prototyping, Prototipificación rápida, Solidification, Solidificación, Erstarren, Procédé LENS, Laser engineered net shapin process, Contour method: Residual stresses, and Laser engineered net shaping (LENS®)

During manufacturing of components by laser engineered net shaping (LENS®), a solid freeform fabrication process, the introduction of residual stresses causes deformation or in the worst case, cracking. The origin is attributed to thermal transients encountered during solidification. In the absence of reliable predictive models for the residual stresses, measurements are necessary. Residual stresses were measured in LENS® samples of 316 stainless steel and Inconel 718 having simple geometrical shapes by both neutron diffraction and the contour methods. The results by the two methods are compared and discussed in the context of the growth direction during the LENS® process. Surprisingly, the residual stresses are practically uni-axial, with high stresses in the growth direction.

Crystallography, Cristallographie cristallogenèse, Chemical industry parachemical industry, Industrie chimique et parachimique, Metallurgy, welding, Métallurgie, soudage, Condensed state physics, Physique de l'état condensé, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Métallurgie des poudres. Matériaux composites, Powder metallurgy. Composite materials, Technologie, Technology, Métal transition alliage, Transition metal alloy, Metal transición aleación, Uebergangsmetallegierung, Alliage base titane, Titanium base alloys, Alliage binaire, Binary alloy, Aleación binaria, Dureté, Hardness, Dureza, Haerte, Dépôt laser, Laser deposition, Depósito laser, Etude expérimentale, Experimental study, Estudio experimental, Experimentelle Untersuchung, Grosseur grain, Grain size, Grosor grano, Korngroesse, Matériau gradient fonctionnel, Functionnally graded material, Material gradiente functional, Microdureté, Microhardness, Microdureza, Mikrohaerte, Microscopie électronique balayage, Scanning electron microscopy, Microscopía electrónica barrido, Rasterelektronenmikroskopie, Microstructure, Microestructura, Mikrogefuege, Molybdène alliage, Molybdenum alloy, Molibdeno aleación, Molybdaenlegierung, Poudre métallique, Metal powder, Polvo metálico, Metallpulver, Prototypage rapide, Rapid prototyping, Prototipificación rápida, Solidification dirigée, Directional solidification, Solidificación dirigida, Gerichtete Erstarrung, Vanadium alliage, Vanadium alloy, Vanadio aleación, Vanadiumlegierung, Alliage TiMo, Alliage TiV, Procédé LENS, Laser engineered net shaping, Ti Mo, Ti V, Graded alloy, and Titanium -vanadium alloy

Compositionally graded binary titanium-vanadium and titanium-molybdenum alloys have been deposited using the laser engineered net-shaping ( LENS ) process. A compositional gradient, from elemental Ti to Ti-25at.% V or Ti -25at.% Mo, has been achieved within a length of ∼ 25 mm. The feedstock used for depositing the graded alloy consists of elemental Ti and V (or Mo) powders. Though the microstructural features across the graded alloy correspond to those typically observed in α/β Ti alloys, the scale of the features is refined in a number of cases. Microhardness measurements across the graded samples exhibit an increase in hardness with increasing alloying content up to a composition of ∼ 12% in case of Ti-xV and up to a composition of - 10% in case of the Ti-xMo alloys. Further increase in the alloying content resulted in a decrease in hardness for both the Ti-xV as well as the Ti-x Mo alloys. A notable feature of these graded deposits is the large prior β grain size resulting from the directionally solidified nature of the microstructure. Thus, grains ∼ 10 mm in length grows in a direction perpendicular to the substrate. The ability to achieve such substantial changes in composition across rather limited length makes this process a highly attractive candidate for combinatorial materials science studies.