A review on microstructures and properties of high entropy alloys manufactured by selective laser melting

Zhang, Chen; Zhu, Junkai; Zheng, Hao; Li, Hui; Liu, Sheng; Cheng, Gary J.

doi:10.1088/2631-7990/ab9ead

Cited by 93 publications

(28 citation statements)

References 121 publications

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“…29 The higher residual stress increases the dislocation density in walls built with bidirectional strategy, which increases the material hardness. 30 However, it is observed that the micro-hardness of the wall structures built with both the strategies is lower than the micro-hardness of LDED built bulk structures at the same process parameters 22 as presented in Figure 12. This is largely due to relatively lower cooling rates in wall structures as compared to bulk structures.…”

Section: Mechanical Characterizationsmentioning

confidence: 91%

Effect of scan pattern on Hastelloy-X wall structures built by laser-directed energy deposition-based additive manufacturing

Jinoop

Nayak

Yadav

et al. 2021

Journal of Micromanufacturing

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This article systematically analyzes the effect of scan pattern on the geometry and material properties of wall structures built using laser-directed energy deposition (LDED)-based additive manufacturing. Hastelloy-X (Hast-X), a nickel superalloy, is deposited using an indigenously developed 2-kW fiber laser–based LDED system. The wall structures are built using unidirectional and bidirectional scan patterns with the same LDED process parameters and effect of scan pattern on the geometry, microstructural and mechanical characteristics of Hast-X wall structures built using LDED. The wall width is higher for samples deposited with the bidirectional pattern at the starting and ending points as compared to walls built with the unidirectional pattern. Further, the range of width value is higher for walls built with bidirectional strategy as compared to walls built with unidirectional strategy. Wall height is more uniform with unidirectional deposition at the central region, with the range and standard deviation for walls built using bidirectional deposition at 3 and 2.5 times more than unidirectional deposition, respectively. The deposition rate for bidirectional deposition is two times that of unidirectional deposition. The microstructure of the built walls is cellular/dendritic, with bidirectional deposition showing a finer grain structure. Elemental mapping shows the presence of elemental segregation of Mo, C and Si, confirming the formation of Mo-rich carbides. Micro-hardness and ball indentation studies reveal higher mechanical strength for samples built using the bidirectional pattern, with unidirectional samples showing strength lower than the conventional wrought Hast-X samples (197 HV). This study paves a way to understand the effect of scan pattern on LDED built wall structures for building intricate thin-walled components.

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Section: Mechanical Characterizationsmentioning

confidence: 91%

Effect of scan pattern on Hastelloy-X wall structures built by laser-directed energy deposition-based additive manufacturing

Jinoop

Nayak

Yadav

et al. 2021

Journal of Micromanufacturing

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“…Recently, many HEA systems have been exploited, and most research focused on the microstructure and properties of the AlxCoCrFeNi HEAs system [20][21][22]. The addition of copper (Cu) to a HEA matrix has been widely investigated [23]; this is probably because the atomic radii of elements are close to one another and because there is a tendency to form a reliable solution according to the phase rule and phase diagram between them [24].…”

Section: Introductionmentioning

confidence: 99%

Effect of Copper Addition on the AlCoCrFeNi High Entropy Alloys Properties via the Electroless Plating and Powder Metallurgy Technique

et al. 2021

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To improve the AlCoCrFeNi high entropy alloys’ (HEAs’) toughness, it was coated with different amounts of Cu then fabricated by the powder metallurgy technique. Mechanical alloying of equiatomic AlCoCrFeNi HEAs for 25 h preceded the coating process. The established powder samples were sintered at different temperatures in a vacuum furnace. The HEAs samples sintered at 950˚C exhibit the highest relative density. The AlCoCrFeNi HEAs model sample was not successfully produced by the applied method due to the low melting point of aluminum. The Al element’s problem disappeared due to encapsulating it with a copper layer during the coating process. Because the atomic radius of the copper metal (0.1278 nm) is less than the atomic radius of the aluminum metal (0.1431 nm) and nearly equal to the rest of the other elements (Co, Cr, Fe, and Ni), the crystal size powder and fabricated samples decreased by increasing the content of the Cu wt%. On the other hand, the lattice strain increased. The microstructure revealed that the complete diffusion between the different elements to form high entropy alloy material was not achieved. A dramatic decrease in the produced samples’ hardness was observed where it decreased from 403 HV at 5 wt% Cu to 191 HV at 20 wt% Cu. On the contrary, the compressive strength increased from 400.034 MPa at 5 wt% Cu to 599.527 MPa at 15 wt% Cu with a 49.86% increment. This increment in the compressive strength may be due to precipitating the copper metal on the particles’ surface in the nano-size, reducing the dislocations’ motion, increasing the stiffness of produced materials. The formability and toughness of the fabricated materials improved by increasing the copper’s content. The thermal expansion has increased gradually by increasing the Cu wt%.

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“…High entropy alloys (HEAs) are classically defined as the multi-principal element alloys (MPEAs) formed by mixing equal or near-equal amounts of five or more elements, and they have been ascribed to possess four major characteristics, namely, high-entropy effect, sluggish diffusion effect, severe lattice distortion effect and cocktail effect [1][2][3][4] . On the other hand, the alloys consisting of three or four principal (base) elements in equal or near-equal atomic compositions are defined as medium entropy alloys (MEAs) [5].…”

Section: Introductionmentioning

confidence: 99%

pyMPEALab Toolkit for Accelerating Phase Design in Multi-principal Element Alloys

et al. 2021

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Multi-principal element alloys (MPEAs) occur at or nearby the centre of the multicomponent phase space, and they have the unique potential to be tailored with a blend of several desirable properties for the development of materials of future. The lack of universal phase diagrams for MPEAs has been a major challenge in the accelerated design of products with these materials. This study aims to solve this issue by employing data-driven approaches in phase prediction. A MPEA is first represented by numerical fingerprints (composition, atomic size difference , electronegativity , enthalpy of mixing , entropy of mixing , dimensionless $$\Omega$$ Ω parameter, valence electron concentration and phase types ), and an artificial neural network (ANN) is developed upon the datasets of these numerical descriptors. A pyMPEALab GUI interface is developed on the top of this ANN model with a computational capability to associate composition features with remaining other input features. With the GUI interface, an user can predict the phase(s) of a MPEA by entering solely the information of composition. It is further explored on how the knowledge of phase(s) prediction in composition-varied $$\hbox {Al}_x$$ Al x CrCoFeMnNi and $$\hbox {CoCrNiNb}_x$$ CoCrNiNb x can help in understanding the mechanical behavior of these MPEAs. Graphic Abstract

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A review on microstructures and properties of high entropy alloys manufactured by selective laser melting

Cited by 93 publications

References 121 publications

Effect of scan pattern on Hastelloy-X wall structures built by laser-directed energy deposition-based additive manufacturing

Effect of scan pattern on Hastelloy-X wall structures built by laser-directed energy deposition-based additive manufacturing

Effect of Copper Addition on the AlCoCrFeNi High Entropy Alloys Properties via the Electroless Plating and Powder Metallurgy Technique

pyMPEALab Toolkit for Accelerating Phase Design in Multi-principal Element Alloys

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