3D printing of Aluminium alloys: Additive Manufacturing of Aluminium alloys using selective laser melting

The Role of Additive Manufacturing in the Era of Industry 4.0

Additive manufacturing (AM) or three-dimensional (3D) printing has introduced a novel production method in design, manufacturing, and distribution to end-users. This technology has provided great freedom in design for creating complex components, highly customizable products, and efficient waste minimization. The last industrial revolution, namely industry 4.0, employs the integration of smart manufacturing systems and developed information technologies. Accordingly, AM plays a principal role in industry 4.0 thanks to numerous benefits, such as time and material saving, rapid prototyping, high efficiency, and decentralized production methods. This review paper is to organize a comprehensive study on AM technology and present the latest achievements and industrial applications. Besides that, this paper investigates the sustainability dimensions of the AM process and the added values in economic, social, and environment sections. Finally, the paper concludes by pointing out the future trend of AM in technology, applications, and materials aspects that have the potential to come up with new ideas for the future of AM explorations.

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The Potential of Additive Manufacturing in the Smart Factory Industrial 4.0: A Review

Powder Bed Fusion (PBF) techniques constitute a family of Additive Manufacturing (AM) processes, which are characterised by high design flexibility and no tooling requirement. This makes PBF techniques attractive to many modern manufacturing sectors (e.g. aerospace, defence, energy and automotive) where some materials, such as Nickel-based superalloys, cannot be easily processed using conventional subtractive techniques. Nickel-based superalloys are crucial materials in modern engineering and underpin the performance of many advanced mechanical systems. Their physical properties (high mechanical integrity at high temperature) make them difficult to process via traditional techniques. Consequently, manufacture of nickel-based superalloys using PBF platforms has attracted significant attention. To permit a wider application, a deep understanding of their mechanical behaviour and relation to process needs to be achieved. The motivation for this paper is to provide a comprehensive review of the mechanical properties of PBF nickel-based superalloys and how process parameters affect these, and to aid practitioners in identifying the shortcomings and the opportunities in this field. Therefore, this paper aims to review research contributions regarding the microstructure and mechanical properties of nickel-based superalloys, manufactured using the two principle PBF techniques: Laser Powder Bed Fusion (LPBF) and Electron Beam Melting (EBM). The ‘target’ microstructures are introduced alongside the characteristics of those produced by PBF process, followed by an overview of the most used building processes, as well as build quality inspection techniques. A comprehensive evaluation of the mechanical properties, including tensile strength, hardness, shear strength, fatigue resistance, creep resistance and fracture toughness of PBF nickel-based superalloys are analysed. This work concludes with summary tables for data published on these properties serving as a quick reference to scholars. Characteristic process factors influencing functional performance are also discussed and compared throughout for the purpose of identifying research opportunities and directing the research community toward the end goal of achieving part integrity that extends beyond static components only.

Powder Bed Fusion of nickel-based superalloys: A review

Emerging metallic systems for additive manufacturing : in-situ alloying and multi-metal processing in laser powder bed fusion

Synthesis of Ti-5Al, Ti-6Al-7Nb, and Ti-22Al-25Nb alloys from elemental powders using powder-bed fusion additive manufacturing

In-situ synthesis of Ti2AlNb-based intermetallic alloy by selective laser melting

Causes of the appearance of anisotropy of properties in products manufactured according to the technology of selective laser melting of metallic powder materials are investigated. The results of an evaluation of mechanical properties of the samples made of Ti–6Al–4V and VT6 titanium-based alloys and Inconel 718 refractory nickel alloy in various directions are presented. The dependence of their mechanical properties on the orientation of billets relative to the working platform of the installation is presented. An analysis of microslices of the Ti–6Al–4V alloy showed that the direction of the granular structure for a rectangular sample corresponds to the growth direction, while, when manufacturing thin elements of a net construction, other thermal processes flow due to their smaller cross section, which affects the crystallization conditions and microstructure being formed. Grain directions and shapes change depending on the slope angle of the element of the net structure.

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Anisotropy of mechanical properties of products manufactured using selective laser melting of powdered materials

The development of new, more refractory heat-resistant materials for gas-turbine engines is one of most important problems of modern materials science. This is associated with the fact that nickel superalloys currently used for this purpose have a lower melting point of ~1400°C, which limits their own maximal working temperature by a range of 1100–1150°C. The Ni alloys can be replaced by natural composites, in which refractory metals are a matrix, while their silicides are intermetallic hardeners. Only three “refractory metal–silicon” binary systems manifest stability to the Me5Si3 silicide, notably, Nb5Si3, Re5Si3, and W5Si3. From the viewpoint of a combination of a high melting point and a low density, the Nb5Si3 compound is optimal among other silicides. The use of alloys of the Nb–Si system in additive manufacturing machines is of considerable interest. This work presents the results of experimental investigations into the treatment of the Nb–16 at % Si powder fabricated using mechanical alloying of elemental Nb and Si powders in the thermal plasma flux. The Nb–16Si alloy powder is fabricated by the mechanical alloying of powders of pure elements in a Fritsch Pulverisette 4 planetary mill. The powder spheroidization is performed in a plasma installation based on a discharge vortex-stabilized electric-arc thermal plasma generator. Based on the results of experimental investigations, the principal possibility to perform the plasma spheroidization of particles of the Nb–16Si alloy prepared by mechanical alloying is shown. It is shown that the surface of spheroidized particles is rough and reflects the cast material structure. Three phase components Nb5Si3, Nb3Si, and Nbss having different optical contrast are revealed in microslices, which is confirmed by X-ray phase analysis.

Fabrication of the Nb–16Si Alloy Powder for Additive Technologies by Mechanical Alloying and Spheroidization in Electric-Arc Discharge Thermal Plasma

The in situ synthesis of the Ti2AlNb-based intermetallic alloy was studied using selective laser melting of powder materials. The object of research was the Ti–22Al–25Nb (at %) alloy, the main phase of which is the Ti2AlNb intermetallic compound with an ordered orthorhombic lattice (O phase). The Ti–22Al–25Nb alloy has high mechanical properties both at room temperature and at elevated temperatures, as well as a low specific weight, and is considered a promising material for use in the aerospace industry. To perform the experiments, a mechanical mixture of pure powders of titanium, aluminum, and niobium in a ratio necessary to synthesize the Ti–22Al–25Nb alloy was used. Selective laser melting relating to additive technologies is most promising to fabricate parts by the layer-by-layer addition of materials. The use of this technology makes it possible to fabricate complexly shaped parts based on the CAD model data. Compact samples for the investigation are performed by selective laser melting. The microstructure, density, phase composition, and microhardness of these samples are investigated. The influence of the thermal treatment in the form of homogenization at 1250°C for 2.5 h and subsequent aging at 900°C for 24 h on the microstructure, phase composition, and chemical homogeneity of the samples is also investigated. It is shown that the compact material formed by selective laser melting contains unmolten niobium particles. Homogenizing annealing makes it possible to attain the complete dissolution these particles in the material; due to this, the material microstructure consists of B2 phase grains of various sizes and needlelike precipitates of the orthorhombic phase.

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A. V. Grigoriev

Papers

Synthesis of Ti-5Al, Ti-6Al-7Nb, and Ti-22Al-25Nb alloys from elemental powders using powder-bed fusion additive manufacturing

In-situ synthesis of Ti2AlNb-based intermetallic alloy by selective laser melting

Anisotropy of mechanical properties of products manufactured using selective laser melting of powdered materials

Fabrication of the Nb–16Si Alloy Powder for Additive Technologies by Mechanical Alloying and Spheroidization in Electric-Arc Discharge Thermal Plasma

Selective Laser Melting of the Intermetallic Titanium Alloy