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Additive Manufacturing and Welding Technologies for High-Entropy Alloys and Dissimilar Metals

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A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Metals and Alloys".

Deadline for manuscript submissions: closed (20 January 2024) | Viewed by 18165

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Dr. Dejia Liu

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School of Materials Science and Engineering, East China Jiaotong University, Shuang Gang Dong Jie 808#, Economic and Technological Development Zone, Nanchang 330013, China
Interests: high-entropy alloys; high-entropy filler metals; multi-principal filler materials; dissimilar metal welding; laser welding; microstructure evolution; intermetallic compounds; mechanical properties; Ti/steel bimetallic sheet; Al/steel joints.

Prof. Dr. Longzhi Zhao

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Dear Colleagues,

High-entropy alloys (HEAs) are defined as alloys with five or more principal elements. Each principal element has a concentration of 5~35 at.%. The multi-principal-element character of HEAs presents some important effects, including the high-entropy, sluggish diffusion, severe-lattice-distortion, and cocktail effects. These factors are much less pronounced in conventional alloys. Owing to the unique multi-principal-element composition, HEAs can possess special properties, including high strength/hardness, outstanding wear resistance, exceptional high-temperature strength, good structural stability, and good corrosion and oxidation resistance. Some of these properties are not observed in conventional alloys, making HEAs attractive in many fields, such as aerospace, nuclear energy, chemical plants, and marine vessels.

As the key processing methods, the additive manufacturing and welding technologies of high-entropy alloys have an impact on the future applications and technological developments of HEAs. The selection of feasible processes with optimized parameters is essential to enhance the applications of HEAs. However, the structure of HEAs varies with material systems, welding methods, and parameters. A systemic understanding of the structures and properties of the processed samples is directly relevant to the application of HEAs. Therefore, it is significantly meaningful to study in-depth the intrinsic relationship among the material systems, processing methods, process parameters, microstructure, and mechanical properties of HEAs during the additive manufacturing and welding processes.

The current Special Issue aims to explore the advanced additive manufacturing and welding technologies of HEAs and to study the basic principles of microstructure and property regulations. The articles presented in this Special Issue will address various topics, ranging from, but not limited to, the design of novel types of HEAs, the exploration of advanced welding technologies, the optimization of process parameters, microstructure regulation, and the performance improvement of HEAs.

Dr. Dejia Liu
Prof. Dr. Longzhi Zhao
Guest Editors

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Keywords

high-entropy alloys
welding
additive manufacturing
microstructure evolution
mechanical properties
filler metals
welding mechanism
joint performance

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Published Papers (11 papers)

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Research

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13 pages, 4550 KiB

Open AccessArticle

Laser Welding of Titanium/Steel Bimetallic Sheets with In Situ Formation of Fe_x(CoCrNiMn)Ti_y High-Entropy Alloys in Weld Metal

by Dejia Liu, Zhe Ma, Nianlong Xue, Weixiong Wang and Shanguo Han

Materials 2024, 17(3), 623; https://doi.org/10.3390/ma17030623 - 27 Jan 2024

Cited by 2 | Viewed by 1356

Abstract

Due to the notable disparities in the physical and chemical characteristics between titanium and steel, the direct fusion of titanium/steel bimetallic sheets results in a considerable formation of fragile intermetallic compounds, making it difficult to achieve excellent metallurgical welded joints. In this study, a multi-principal powder of CoCrNiMn was designed and utilized as a filler material in the welding of the TA1/Q345 bimetallic sheet. It was expected that the in situ formation of Fe_x(CoCrNiMn)Ti_y high-entropy alloys would be achieved using the filler powders, combined with the Ti and Fe elements from the melting of the TA1 and Q345 so as to restrain the generation of Fe-Ti IMCs and obtain the promising welded joints of the TA1/Q345 bimetallic sheet. An interesting finding is that high-entropy alloys were successfully obtained in the weld metal. The Fe-Ti intermetallic compounds at the welding interface were significantly reduced. The tensile strength was ~293 MPa, accounting for 60% of the strength of the base metal. Dimples were observed at the fracture of the welded joint. Full article

(This article belongs to the Special Issue Additive Manufacturing and Welding Technologies for High-Entropy Alloys and Dissimilar Metals)

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12 pages, 11096 KiB

Open AccessArticle

Effect of Thermal Aging on the Microstructure and Mechanical Properties of ER308L/Z2CND18.12N2 Dissimilar Welds

by Hongmin Ju, Jing Liu, Shiwei Zhuo, Yanli Wang and Shilei Li

Materials 2023, 16(22), 7119; https://doi.org/10.3390/ma16227119 - 10 Nov 2023

Viewed by 1313

Abstract

A multi-analytical approach was used to investigate the effect of thermal aging on the microstructure and mechanical properties of ER308L/Z2CND18.12N2. The results demonstrated that fractures occurred preferentially on the ER308L side. Z2CND18.12N2 exhibited superior fracture toughness compared to ER308L regardless of thermal aging time. The ultimate tensile strength significantly increased from 564.5 MPa in the unaged condition to 592.7 MPa to MPa after thermal aging and the fracture mode changed from ductile fracture into a ductile + quasi-cleavage fracture. The fusion zone (FZ) with the chemical composition gradient was about 40 μm from the Z2CND18.12N2 to ER308L. After thermal aging, spinodal decomposition and G-phase precipitation were observed for the first time in the ferrite phase of the FZ. Moreover, the hardness presented the following trend: FZ > ER308L > Z2CND18.12N2. The hardness of the ferrite phase dramatically increased from 6.13 GPa in an unaged condition to 8.46 GPa in a 10,000 h aged condition. Full article

(This article belongs to the Special Issue Additive Manufacturing and Welding Technologies for High-Entropy Alloys and Dissimilar Metals)

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11 pages, 7898 KiB

Open AccessArticle

Preparation of VZrHfNbTa High-Entropy Alloy-Based High-Temperature Oxidation-Resistant Coating and Its Bonding Mechanism

by Mengjun Hu, Rui Tan, Xiaojuan Jiang, Mengyao Dong, Junyu Chen, Meilong Hu and Yu Yang

Materials 2023, 16(17), 5976; https://doi.org/10.3390/ma16175976 - 31 Aug 2023

Viewed by 1258

Abstract

Ultra-high Temperature Oxidation-Resistant Alloys (UTORAs) have received a lot of attention due to the increased research demand for deep space exploration around the world. However, UTORAs have the disadvantages of easy oxidation and chalking. So, in this study, a UTORAs is prepared by hot-press sintering on VZrHfNbTa (HEA: High Entropy Alloys can generally be defined as more than five elements by the equal atomic ratio or close to the equal atomic ratio alloying, the mixing entropy is higher than the melting entropy of the alloy, generally forming a high entropy solid solution phase of a class of alloys.) a substrate coated with hafnium. The bonding mechanism, resistance to high-temperature oxidation, and hardness of the sample tests are carried out. The results show that zirconium in the matrix will diffuse into the hafnium coating during the high-temperature sintering process and form the HfZr alloy transition layer, the coating thickness of the composite is about 120 μm, and the diffusion distance of zirconium in the hafnium coating is about 60 μm, this transition layer chemically combines the hafnium coating and the HEA substrate into a monolithic alloy composite. The results of high-temperature oxidation experiments show that the oxidation degree of the hafnium-coated VZrHfNbTa composite material is significantly lower than that of the VZrHfNbTa HEA after oxidation in air at 1600 °C for 5 h. The weight gain of the coated sample after oxidation is 56.56 mg/cm², which is only 57.7% compared to the weight gain of the uncoated sample (98.09 mg/cm² for uncoated), and the surface of the uncoated HEA shows obvious dents, oxidation, and pulverization occurred on the surface and interior of the sample. In contrast, the coated composite alloy sample mainly undergoes surface oxidation sintering to form a dense HfO₂ protective layer, and the internal oxidation of the hafnium-coated VZrHfNbTa composite alloy is significantly lower than that of the uncoated VZrHfNbTa HEA. Full article

(This article belongs to the Special Issue Additive Manufacturing and Welding Technologies for High-Entropy Alloys and Dissimilar Metals)

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11 pages, 4269 KiB

Open AccessArticle

Prediction and Experimental Evaluation of Mechanical Properties of SiC-Reinforced Ti-4.25Al-2V Matrix Composites Produced by Laser Direct Energy Deposition

by Ilya Magidov, Konstanitin Mikhaylovskiy, Svetlana Shalnova, Ilya Topalov, Marina Gushchina, Sergey Zherebtsov and Olga Klimova-Korsmik

Materials 2023, 16(15), 5233; https://doi.org/10.3390/ma16155233 - 25 Jul 2023

Cited by 2 | Viewed by 1481

Abstract

An important direction in the development of additive technologies is associated with the addition of ceramic particles (oxide, carbide, boride, and nitride ceramics) to metal powders. The prediction of the physical and mechanical characteristics of SiC-particle-reinforced composite materials (PRCMs) in comparison with experimental results was studied. A near-α Ti-4.25Al-2V titanium-alloy-based composite reinforced by 1 vol.% of SiC ceramic particles was produced using laser direct energy deposition. A multiscale modeling approach at the micro and macro levels was applied. At the micro level, the toughness and strength characteristics for a temperature interval of T = 20–450 °C were predicted using a representative volume element of PRCM with the nearly real shape of SiC particles. At the macro level, the features of plastic deformation and fracture of the PRCM were predicted by numerical modeling using the commercial software Digimat Student Edition ver. 2022.4 and Ansys Student 2023 R2. The addition of SiC particles was found to improve the physical and mechanical properties in the whole temperature range. The results of the numerical modeling were consistent with the experimental data (the deviation did not exceed 10%). The proposed approach for predicting the physical and mechanical properties of Ti-4.25Al-2V/SiC can also be used for other PRCMs obtained by laser direct energy deposition. Full article

(This article belongs to the Special Issue Additive Manufacturing and Welding Technologies for High-Entropy Alloys and Dissimilar Metals)

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16 pages, 12144 KiB

Open AccessArticle

Numerical Strength Analysis of Laser-Welded Differential Housing and Gear Considering Residual Stress

by Liuping Wang, Zhengshun Ni, Yingang Xiao, Yongqiang Li, Xianghuan Liu, Yongzhi Chen, Shuanghao Cui, Dejun Zhang, Chengji Mi and Quanguo He

Materials 2023, 16(13), 4721; https://doi.org/10.3390/ma16134721 - 29 Jun 2023

Cited by 2 | Viewed by 1483

Abstract

In order to avoid slackening of differential housing and gear joined by bolts, the laser-welding process is proposed in this paper, and the strength of a connecting joint was estimated by numerical analysis with consideration of welding residual stress. The process parameters of laser welding for dissimilar materials QT600 cast iron and 20MnCr5 structural alloy steel were introduced, and chemical composition analysis and microstructure analysis were conducted on the welded joints. The finite element model of laser-welded differential housing and gear was established to obtain the welding residual stress by applying a moving heat source. To verify the accuracy of the simulated result, static pressing tests were employed. The maximum tensile residual stress was 319.4 MPa, located at the same point as the maximum temperature. The simulated stress agreed well with the experimental data. Finally, the dynamic strength of laser-welded differential housing and gear under forward, reverse, and start-up conditions was assessed by regarding welding residual stress as the initial stress field, which showed that all safety factors were greater than 1.4. Full article

(This article belongs to the Special Issue Additive Manufacturing and Welding Technologies for High-Entropy Alloys and Dissimilar Metals)

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12 pages, 7814 KiB

Open AccessArticle

Interlayer Tailoring of Ti–6Al–4V and 17-4PH Stainless Steel Joint by Tungsten Inert Gas Welding

by Raj Narayan Hajra, Chan Woong Park, Kyunsuk Choi and Jeoung Han Kim

Materials 2023, 16(12), 4370; https://doi.org/10.3390/ma16124370 - 14 Jun 2023

Cited by 5 | Viewed by 1566

Abstract

The development of robust and efficient methods for constructing and joining complex metal specimens with high bonding quality and durability is of paramount importance for various industries, e.g., aerospace, deep space, and automobiles. This study investigated the fabrication and characterization of two types of multilayered specimens prepared by tungsten inert gas (TIG) welding: Ti–6Al–4V/V/Cu/Monel400/17-4PH (Specimen 1) and Ti–6Al–4V/Nb/Ni–Ti/Ni–Cr/17-4PH (Specimen 2). The specimens were fabricated by depositing individual layers of each material onto a Ti–6Al–4V base plate, and subsequently welding them to the 17-4PH steel. The specimens exhibited an effective internal bonding without any cracks, accompanied by a high tensile strength, with Specimen 1 exhibiting a significantly higher tensile strength than Specimen 2. However, the substantial interlayer penetration of Fe and Ni in the Cu and Monel layers of Specimen 1 and the diffusion of Ti along the Nb and Ni–Ti layers in Specimen 2 resulted in a nonuniform elemental distribution, raising concerns about the lamination quality. This study successfully achieved elemental separation of Fe/Ti and V/Fe, which is vital for preventing the formation of detrimental intermetallic compounds, particularly in the fabrication of complex multilayered specimens, representing the prime novelty of this work. Our study highlights the potential of TIG welding for the fabrication of complex specimens with high bonding quality and durability. Full article

(This article belongs to the Special Issue Additive Manufacturing and Welding Technologies for High-Entropy Alloys and Dissimilar Metals)

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13 pages, 7831 KiB

Open AccessArticle

Study on Corrosion Resistance of Stainless-Steel Welded Joints with SnSb8Cu4 and SnZn9

by Jintao Wang, Shengxi Wang, Bo Wang, Xiaohui Han, Yong Liu, Jiehe Ye and Zhan Cheng

Materials 2023, 16(11), 3908; https://doi.org/10.3390/ma16113908 - 23 May 2023

Viewed by 1388

Abstract

The use of soldering based on metallurgical bonding, as opposed to conventional rubber sealing, is capable of achieving the firm sealing of stainless-steel subway car bodies, though the corrosion resistance of such joints has rarely been investigated. In this study, two typical solders were selected and applied to the soldering of stainless steel, and their properties were investigated. As indicated by the experimental results, the two types of solder exhibited favorable wetting and spreading properties on stainless-steel plates, and successfully achieved sealing connections between the stainless-steel sheets. In comparison with the Sn-Zn9 solder, the Sn-Sb8-Cu4 solder exhibited lower solidus–liquidus, such that it can be more suitably applied to low-temperature sealing brazing. The sealing strength of the two solders reached over 35 MPa, notably higher than that of the sealant currently used (the sealing strength is lower than 10 MPa). In comparison with the Sn-Sb8-Cu4 solder, the Sn-Zn9 solder exhibited a higher corrosion tendency and a higher degree of corrosion during the corrosion process. Full article

(This article belongs to the Special Issue Additive Manufacturing and Welding Technologies for High-Entropy Alloys and Dissimilar Metals)

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11 pages, 7995 KiB

Open AccessArticle

Crack Inhibition and Performance Modification of NiCoCr-Based Superalloy with Y₂O₃ Nanoparticles by Laser Metal Deposition

by Xiaodong Li, Jiaxin Du, Jijin Xu, Shuai Wang, Mengling Shen and Chuanhai Jiang

Materials 2023, 16(10), 3616; https://doi.org/10.3390/ma16103616 - 9 May 2023

Cited by 4 | Viewed by 1773

Abstract

A new precipitation strengthening NiCoCr-based superalloy with favorable mechanical performance and corrosion resistance was designed for ultra-supercritical power generation equipment. The degradation of mechanical properties and steam corrosion at high temperatures put forward higher requirements for alternative alloy materials; however, when the superalloy is processed to form complex shaped components through advanced additive manufacturing techniques such as laser metal deposition (LMD), hot cracks are prone to appear. This study proposed that microcracks in LMD alloys could be alleviated with powder decorated by Y₂O₃ nanoparticles. The results show that adding 0.5 wt.% Y₂O₃ can refine grains significantly. The increase in grain boundaries makes the residual thermal stress more uniform to reduces the risk of hot cracking. In addition, the addition of Y₂O₃ nanoparticles enhanced the ultimate tensile strength of the superalloy at room temperature by 18.3% compared to original superalloy. The corrosion resistance was also improved with 0.5 wt.% Y₂O₃, which was attributed to the reduction of defects and the addition of inert nanoparticles. Full article

(This article belongs to the Special Issue Additive Manufacturing and Welding Technologies for High-Entropy Alloys and Dissimilar Metals)

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18 pages, 15244 KiB

Open AccessArticle

Mechanical Behavior of a Medium-Entropy Fe₆₅(CoNi)₂₅Cr_9.5C_0.5 Alloy Produced by Selective Laser Melting

by Elizaveta Povolyaeva, Dmitry Shaysultanov, Ilya Astakhov, Stanislav Evlashin, Margarita Klimova, Nikita Stepanov and Sergey Zherebtsov

Materials 2023, 16(8), 3193; https://doi.org/10.3390/ma16083193 - 18 Apr 2023

Cited by 2 | Viewed by 1828

Abstract

Specimens of a medium-entropy Fe₆₅(CoNi)₂₅Cr_9.5C_0.5 (in at.%) alloy were produced using additive manufacturing (selective laser melting, SLM). The selected parameters of SLM resulted in a very high density in the specimens with a residual porosity of less than 0.5%. The structure and mechanical behavior of the alloy were studied under tension at room and cryogenic temperatures. The microstructure of the alloy produced by SLM comprised an elongated substructure, inside which cells with a size of ~300 nm were observed. The as-produced alloy demonstrated high yield strength and ultimate tensile strength (YS = 680 MPa; UTS = 1800 MPa) along with good ductility (tensile elongation = 26%) at a cryogenic temperature (77 K) that was associated with the development of transformation-induced plasticity (TRIP) effect. At room temperature, the TRIP effect was less pronounced. Consequently, the alloy demonstrated lower strain hardening and a YS/UTS of 560/640 MPa. The deformation mechanisms of the alloy are discussed. Full article

(This article belongs to the Special Issue Additive Manufacturing and Welding Technologies for High-Entropy Alloys and Dissimilar Metals)

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18 pages, 9453 KiB

Open AccessArticle

Effects of Heat Treatment on the Interface Microstructure and Mechanical Properties of Friction-Stir-Processed AlCoCrFeNi/A356 Composites

by Shengqing Hu, Kai Wang, Simu Ma, Haoran Qi, Naijun He and Fuguo Li

Materials 2023, 16(6), 2234; https://doi.org/10.3390/ma16062234 - 10 Mar 2023

Cited by 3 | Viewed by 1819

Abstract

Equiatomic AlCoCrFeNi high-entropy alloy (HEA) has gained significant interest in recent years because of its excellent mechanical properties. A356 aluminum alloy reinforced by AlCoCrFeNi HEA particles was fabricated by friction stir processing (FSP) and subsequent heat treatment. Solution and aging treatments were specially performed for the composites to control the interface microstructure, and interfacial microstructure and tensile properties were explored at different conditions. The interface between the matrix and HEA particles showed a dual-layered core–shell structure and the thickness of the shell region increased with the solution time. The microstructure located in the shell layers consisted of a solid solution with increasing aluminum content, in which a radial-shaped solid solution phase formed in the region close to the core of the HEA particle and scattered solid solution grains with high Ni content formed in the region close to the matrix alloy. The gradient of composition and microstructure across the HEA/Al interface can be obtained through heat treatment, and an optimal interface bonding state and mechanical property were obtained after solution treatment for 2 h. Compared with FSPed A356 aluminum alloy, the FSPed composite enhanced the tensile stress by 60 MPa and the stain by 5% under the optimized conditions. The overgrowth of the shell layer decreased both the tensile strength and the ductile greatly due to the formation of a radial-shaped solid solution phase in the shell region. Full article

(This article belongs to the Special Issue Additive Manufacturing and Welding Technologies for High-Entropy Alloys and Dissimilar Metals)

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Review

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26 pages, 29298 KiB

Open AccessReview

Advances and Challenges in Predictive Modeling for Additive Manufacturing of Dissimilar Metals and Complex Alloys

by Debajyoti Adak, Praveen Sreeramagiri, Somnath Roy and Ganesh Balasubramanian

Materials 2023, 16(16), 5680; https://doi.org/10.3390/ma16165680 - 18 Aug 2023

Cited by 3 | Viewed by 2090

Abstract

We present a scrutiny on the state of the art and applicability of predictive methods for additive manufacturing (AM) of metals, alloys, and compositionally complex metallic materials, to provide insights from the computational models for AM process optimization. Our work emphasizes the importance of manufacturing parameters on the thermal profiles evinced during processing, and the fundamental insights offered by the models used to simulate metal AM mechanisms. We discuss the methods and assumptions necessary for an educated tradeoff between the efficacy and accuracy of the computational approaches that incorporate multi-physics required to mimic the associated fluid flow phenomena as well as the resulting microstructures. Finally, the current challenges in the existing approaches are summarized and future scopes identified. Full article

(This article belongs to the Special Issue Additive Manufacturing and Welding Technologies for High-Entropy Alloys and Dissimilar Metals)

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