Editorial

4 pages, 194 KiB

Open AccessEditorial

Editorial for the Special Issue on Laser Additive Manufacturing: Design, Processes, Materials and Applications

by Jie Yin, Yang Liu and Ping Zhao

Micromachines 2022, 13(12), 2057; https://doi.org/10.3390/mi13122057 - 24 Nov 2022

Viewed by 897

Laser-based additive manufacturing (LAM) is a revolutionary advanced digital manufacturing technology developed in recent decades, which is also a key strategic technology for technological innovation and industrial sustainability [...] Full article

(This article belongs to the Special Issue Laser Additive Manufacturing: Design, Materials, Processes and Applications)

Research

Jump to: Editorial, Review

12 pages, 4382 KiB

Open AccessArticle

Microstructure Transformation in Laser Additive Manufactured NiTi Alloy with Quasi-In-Situ Compression

by Xiao Yang, Shuo Wang, Hengpei Pan, Congyi Zhang, Jieming Chen, Xinyao Zhang and Lingqing Gao

Micromachines 2022, 13(10), 1642; https://doi.org/10.3390/mi13101642 - 30 Sep 2022

Cited by 1 | Viewed by 1256

Abstract

For NiTi alloys, different additive manufacturing processes may have different compressive recovery capabilities. In particular, there are relatively few studies on the compressive recovery ability of NiTi alloys by the laser-directed energy deposition (LDED) process. In this paper, the compression recovery properties of [...] Read more.

For NiTi alloys, different additive manufacturing processes may have different compressive recovery capabilities. In particular, there are relatively few studies on the compressive recovery ability of NiTi alloys by the laser-directed energy deposition (LDED) process. In this paper, the compression recovery properties of NiTi alloys with the LDED process were investigated quasi-in-situ by means of transmission electron microscopy, an electron backscatter diffractometer, and focused ion beam–fixed-point sample preparation. The results showed that the material can be completely recovered under 4% deformation and the B19’ martensite phase content and dislocation density are basically unchanged. However, the recovery rate was only 90% and the unrecoverable strain was 0.86% at 8% deformation. Meanwhile, the B19’ martensite phase content and dislocation density of the material increased. Furthermore, with the increase in deformation, the relative dislocation pinning effect of the Ti₂Ni precipitated phase in the alloy was enhanced, which reduced the compressive strain recovery to a certain extent. Full article

(This article belongs to the Special Issue Laser Additive Manufacturing: Design, Materials, Processes and Applications)

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15 pages, 12681 KiB

Open AccessArticle

Laser Additive Manufacturing of Anti-Tetrachiral Endovascular Stents with Negative Poisson’s Ratio and Favorable Cytocompatibility

by Ke Chen, Haoran Wan, Xiang Fang and Hongyu Chen

Micromachines 2022, 13(7), 1135; https://doi.org/10.3390/mi13071135 - 18 Jul 2022

Cited by 5 | Viewed by 1844

Abstract

Laser additive manufacturing (LAM) of complex-shaped metallic components offers great potential for fabricating customized endovascular stents. In this study, anti-tetrachiral auxetic stents with negative Poisson ratios (NPR) were designed and fabricated via LAM. Poisson’s ratios of models with different diameters of circular node [...] Read more.

Laser additive manufacturing (LAM) of complex-shaped metallic components offers great potential for fabricating customized endovascular stents. In this study, anti-tetrachiral auxetic stents with negative Poisson ratios (NPR) were designed and fabricated via LAM. Poisson’s ratios of models with different diameters of circular node (DCN) were calculated using finite element analysis (FEA). The experimental method was conducted with the LAM-fabricated anti-tetrachiral stents to validate their NPR effect and the simulation results. The results show that, with the increase in DCN from 0.6 to 1.5 mm, the Poisson ratios of anti-tetrachiral stents varied from −1.03 to −1.12, which is in line with the simulation results. The interrelationship between structural parameters of anti-tetrachiral stents, their mechanical properties and biocompatibility was demonstrated. The anti-tetrachiral stents with a DCN of 0.9 mm showed the highest absolute value of negative Poisson’s ratio, combined with good cytocompatibility. The cytocompatibility tests indicate the envisaged cell viability and adhesion of the vascular endothelial cell on the LAM-fabricated anti-tetrachiral auxetic stents. The manufactured stents exhibit great superiority in the application of endovascular stent implantation due to their high flexibility for easy maneuverability during deployment and enough strength for arterial support. Full article

(This article belongs to the Special Issue Laser Additive Manufacturing: Design, Materials, Processes and Applications)

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15 pages, 6329 KiB

Open AccessArticle

Femtosecond Laser Treatment for Improving the Corrosion Resistance of Selective Laser Melted 17-4PH Stainless Steel

by Lingjian Meng, Jiazhao Long, Huan Yang, Wenjing Shen, Chunbo Li, Can Yang, Meng Wang and Jiaming Li

Micromachines 2022, 13(7), 1089; https://doi.org/10.3390/mi13071089 - 09 Jul 2022

Cited by 6 | Viewed by 1778

Abstract

Currently, laser surface treatment (LST) is considered the most promising method available within the industry. It delivers precise control over surface topography, morphology, wettability, and chemistry, making the technique suitable for regulating the corrosion behavior of alloys. In this paper, femtosecond laser texturing [...] Read more.

Currently, laser surface treatment (LST) is considered the most promising method available within the industry. It delivers precise control over surface topography, morphology, wettability, and chemistry, making the technique suitable for regulating the corrosion behavior of alloys. In this paper, femtosecond laser texturing with different parameters and atmosphere environments was adopted to clarify the effect of surface treatment on the corrosion resistance of selective laser melted (SLM-ed) 17-4PH stainless steel (SS) in a NaCl solution. The experimental results show that, after the heat treatment, the corrosion resistance of the laser-treated samples was enhanced. With the further laser treatment in an argon atmosphere, the oxidation of nanostructural surfaces was avoided. The Cr, Cu, and other alloying elements precipitated on the laser-ablated surface were beneficial to the formation of a passivation film, leading to an improved corrosion resistance performance. Full article

(This article belongs to the Special Issue Laser Additive Manufacturing: Design, Materials, Processes and Applications)

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12 pages, 7124 KiB

Open AccessEditor’s ChoiceArticle

Strain Rate Dependence of Compressive Mechanical Properties of Polyamide and Its Composite Fabricated Using Selective Laser Sintering under Saturated-Water Conditions

by Xiaodong Zheng, Jiahuan Meng and Yang Liu

Micromachines 2022, 13(7), 1041; https://doi.org/10.3390/mi13071041 - 30 Jun 2022

Cited by 3 | Viewed by 1399

Abstract

In this work, polyamide 12 (PA12) and carbon fiber reinforced polyamide 12 (CF/PA12) composites were fabricated using selective laser sintering (SLS), and the coupling effects of the strain rate and hygroscopicity on the compressive mechanical properties were investigated. The results showed that the [...] Read more.

In this work, polyamide 12 (PA12) and carbon fiber reinforced polyamide 12 (CF/PA12) composites were fabricated using selective laser sintering (SLS), and the coupling effects of the strain rate and hygroscopicity on the compressive mechanical properties were investigated. The results showed that the CF/PA12 had a shorter saturation time and lower saturated water absorption under the same conditions, indicating that the SLS of CF/PA12 had lower hydrophilia and higher water resistance when compared to the SLS of PA12. It was observed that as the strain rate increased, and the ultimate compression strength and the yield strength monotonically increased with almost the same slope, indicating that the strain rate had the same positive correlation with the compressive strength of the SLS of PA12 and CF/PA12. The water immersion results showed a significant reduction of 15% in the yield strength of SLS of PA12, but not very significant in CF/PA12. This indicated that the carbon fiber was favorable for maintaining the mechanical properties of polyamide 12 after absorbing water. The findings in this work provide a basic knowledge of the mechanical properties of SLS polyamide under different loading and saturated-water conditions and thus is helpful to widen the application of SLS products in harsh environments. Full article

(This article belongs to the Special Issue Laser Additive Manufacturing: Design, Materials, Processes and Applications)

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15 pages, 3491 KiB

Open AccessArticle

Fabrication of Titanium and Copper-Coated Diamond/Copper Composites via Selective Laser Melting

by Lu Zhang, Yan Li, Simeng Li, Ping Gong, Qiaoyu Chen, Haoze Geng, Minxi Sun, Qinglei Sun and Liang Hao

Micromachines 2022, 13(5), 724; https://doi.org/10.3390/mi13050724 - 30 Apr 2022

Cited by 6 | Viewed by 2482

Abstract

The poor wettability and weak interfacial bonding of diamond/copper composites are due to the incompatibility between diamond and copper which are inorganic nonmetallic and metallic material, respectively, which limit their further application in next-generation heat management materials. Coating copper and titanium on the [...] Read more.

The poor wettability and weak interfacial bonding of diamond/copper composites are due to the incompatibility between diamond and copper which are inorganic nonmetallic and metallic material, respectively, which limit their further application in next-generation heat management materials. Coating copper and titanium on the diamond particle surface could effectively modify and improve the wettability of the diamond/copper interface via electroless plating and evaporation methods, respectively. Here, these dense and complex composites were successfully three-dimensionally printed via selective laser melting. A high thermal conductivity (TC, 336 W/mK) was produced by 3D printing 1 vol.% copper-coated diamond/copper mixed powders at an energy density of 300 J/mm³ (laser power = 180 W and scanning rate = 200 mm/s). 1 and 3 vol.% copper-coated diamond/copper composites had lower coefficients of thermal expansions and higher TCs. They also had stronger bending strengths than the corresponding titanium-coated diamond/copper composites. The interface between copper matrix and diamond reinforcement was well bonded, and there was no cracking in the 1 vol.% copper-coated diamond/copper composite sample. The optimization of the printing parameters and strategy herein is beneficial to develop new approaches for the further construction of a wider range of micro-sized diamond particles reinforced metal matrix composites. Full article

(This article belongs to the Special Issue Laser Additive Manufacturing: Design, Materials, Processes and Applications)

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11 pages, 4156 KiB

Open AccessArticle

Microstructure and Corrosion Behavior of Iron Based Biocomposites Prepared by Laser Additive Manufacturing

by Yan Zhou, Lifeng Xu, Youwen Yang, Jingwen Wang, Dongsheng Wang and Lida Shen

Micromachines 2022, 13(5), 712; https://doi.org/10.3390/mi13050712 - 30 Apr 2022

Cited by 3 | Viewed by 1562

Abstract

Iron (Fe) has attracted great attention as bone repair material owing to its favorable biocompatibility and mechanical properties. However, it degrades too slowly since the corrosion product layer prohibits the contact between the Fe matrix and body fluid. In this work, zinc sulfide [...] Read more.

Iron (Fe) has attracted great attention as bone repair material owing to its favorable biocompatibility and mechanical properties. However, it degrades too slowly since the corrosion product layer prohibits the contact between the Fe matrix and body fluid. In this work, zinc sulfide (ZnS) was introduced into Fe bone implant manufactured using laser additive manufacturing technique. The incorporated ZnS underwent a disproportionation reaction and formed S-containing species, which was able to change the film properties including the semiconductivity, doping concentration, and film dissolution. As a result, it promoted the collapse of the passive film and accelerated the degradation rate of Fe matrix. Immersion tests proved that the Fe matrix experienced severe pitting corrosion with heavy corrosion product. Besides, the in vitro cell testing showed that Fe/ZnS possessed acceptable cell viabilities. This work indicated that Fe/ZnS biocomposite acted as a promising candidate for bone repair material. Full article

(This article belongs to the Special Issue Laser Additive Manufacturing: Design, Materials, Processes and Applications)

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10 pages, 6431 KiB

Open AccessArticle

Microstructure and Wear of W-Particle-Reinforced Al Alloys Prepared by Laser Melt Injection

by Zhidong Xu, Dengzhi Wang, Wenji Song, Congwen Tang, Pengfei Sun, Jiaxing Yang, Qianwu Hu and Xiaoyan Zeng

Micromachines 2022, 13(5), 699; https://doi.org/10.3390/mi13050699 - 29 Apr 2022

Cited by 4 | Viewed by 1424

Abstract

W-particle-reinforced Al alloys were prepared on a 7075 aluminum alloy surface via laser melt injection to improve their wear resistance, and the microstructure, microhardness, and wear resistance of the W/Al layers were studied. Scanning electron microscopy (SEM) results confirmed that a W/Al laser [...] Read more.

W-particle-reinforced Al alloys were prepared on a 7075 aluminum alloy surface via laser melt injection to improve their wear resistance, and the microstructure, microhardness, and wear resistance of the W/Al layers were studied. Scanning electron microscopy (SEM) results confirmed that a W/Al laser melting layer of about 1.5 mm thickness contained W particles, and Al₄W was formed on the surface of the Al alloys. Due to the reinforcement of the W particles and good bonding of the W and Al matrix, the melting layer showed excellent wear resistance compared to that of Al alloys. Full article

(This article belongs to the Special Issue Laser Additive Manufacturing: Design, Materials, Processes and Applications)

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15 pages, 54032 KiB

Open AccessArticle

Study on Interfacial Bonding Properties of NiTi/CuSn10 Dissimilar Materials by Selective Laser Melting

by Changhui Song, Zehua Hu, Yunmian Xiao, Yang Li and Yongqiang Yang

Micromachines 2022, 13(4), 494; https://doi.org/10.3390/mi13040494 - 22 Mar 2022

Cited by 9 | Viewed by 2054

Abstract

The dissimilar materials bonding of NiTi alloy with shape memory effect (SME) and CuSn10 alloy with good ductility, electrical conductivity, and thermal conductivity can be used in aerospace, circuits, etc. In order to integrate NiTi and CuSn10 with greatly different physical and chemical [...] Read more.

The dissimilar materials bonding of NiTi alloy with shape memory effect (SME) and CuSn10 alloy with good ductility, electrical conductivity, and thermal conductivity can be used in aerospace, circuits, etc. In order to integrate NiTi and CuSn10 with greatly different physical and chemical properties by selective laser melting (SLM), the effects of forming interlayers with different SLM process parameters were explored in this study. The defects, microstructure, and component diffusion at the interface were also analyzed. Columnar grain was found along the molten pool boundary of the interfacial region, and grains in the interfacial region were refined. Elements in the interfacial region had a good diffusion. Phase identifying of the interface showed that Ni₄Ti₃ was generated. The analysis showed that the columnar grain, refined grains in the interfacial region, and a certain amount of Ni₄Ti₃ could strengthen the interfacial bonding. This study provides a theoretical basis for forming NiTi/CuSn10 dissimilar materials structural members. Full article

(This article belongs to the Special Issue Laser Additive Manufacturing: Design, Materials, Processes and Applications)

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9 pages, 5643 KiB

Open AccessArticle

Effect of Porosity on Dynamic Response of Additive Manufacturing Ti-6Al-4V Alloys

by Yihang Cui, Jiacheng Cai, Zhiguo Li, Zhenyu Jiao, Ling Hu and Jianbo Hu

Micromachines 2022, 13(3), 408; https://doi.org/10.3390/mi13030408 - 04 Mar 2022

Cited by 14 | Viewed by 2214

Abstract

Additive manufacturing is a rapidly developing manufacturing technology of great potential for applications. One of the merits of AM is that the microstructure of manufactured materials can be actively controlled to meet engineering requirements. In this work, three types of Ti-6Al-4V (TC4) materials [...] Read more.

Additive manufacturing is a rapidly developing manufacturing technology of great potential for applications. One of the merits of AM is that the microstructure of manufactured materials can be actively controlled to meet engineering requirements. In this work, three types of Ti-6Al-4V (TC4) materials with different porosities are manufactured using selective laser melting using different printing parameters. Their dynamic behaviors are then studied by planar impact experiments based on the free-surface velocity measurements and shock-recovery characterizations. Experimental results indicate that the porosity significantly affects their dynamic response, including not only the yield, but also spall behaviors. With the increasing porosity, the Hugoniot elastic limit and spall strength decrease monotonically. In the case of TC4 of a large porosity, it behaves similar to energy-absorbing materials, in which the voids collapse under shock compression and then the spallation takes place. Full article

(This article belongs to the Special Issue Laser Additive Manufacturing: Design, Materials, Processes and Applications)

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13 pages, 4418 KiB

Open AccessEditor’s ChoiceArticle

Hybrid Dissection for Neutron Tube Shell via Continuous-Wave Laser and Ultra-Short Pulse Laser

by Minqiang Kang, Yongfa Qiang, Canlin Zhu, Xiangjun Xiang, Dandan Zhou, Zhitao Peng, Xudong Xie and Qihua Zhu

Micromachines 2022, 13(3), 352; https://doi.org/10.3390/mi13030352 - 23 Feb 2022

Cited by 3 | Viewed by 1451

Abstract

The sealed neutron tube shell dissection process utilizing the traditional lathe turning method suffers from low efficiency and high cost due to the frequency of replacement of the diamond knife. In this study, a hybrid dissection method is introduced by combining the continuous-wave [...] Read more.

The sealed neutron tube shell dissection process utilizing the traditional lathe turning method suffers from low efficiency and high cost due to the frequency of replacement of the diamond knife. In this study, a hybrid dissection method is introduced by combining the continuous-wave (CW) laser for efficient tangential groove production with an ultra-short pulse laser for delamination scanning removal. In this method, a high-power CW laser is firstly employed to make a tapered groove on the shell’s surface, and then a femtosecond pulse laser is used to micromachine the groove in order to obtain a cutting kerf. The thermal field was theoretically investigated in a finite element model. The simulation results show that the width of the area of temperature exceeding 100 °C is 1.9 mm and 0.4 mm with rotating speeds of 20 rad/s and 60 rad/s, respectively. In addition, a 2 mm deep slot in the 25 mm diameter tube was successfully produced in 1 min by a kilowatt fiber laser, and a 500-femtosecond pulse laser was employed to cut a plate with a material removal rate of 0.2 mm³/min. By using the hybrid method, the cutting efficiency was improved about 49 times compared to the femtosecond laser cutting. According to the simulation and experimental results, this method provides a high-efficiency and non-thermal cutting technique for reclaimed metallic neutron tube shells with millimeter-level thick walls, which has the advantages of non-contact, minimal thermal diffusion, and no effect of molten slag. It is indicated that the hybrid dissection method not only offers a new solution for thick neutron tube shell cutting but also extends the application of laser cutting techniques. Full article

(This article belongs to the Special Issue Laser Additive Manufacturing: Design, Materials, Processes and Applications)

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15 pages, 8744 KiB

Open AccessEditor’s ChoiceArticle

Densification, Tailored Microstructure, and Mechanical Properties of Selective Laser Melted Ti–6Al–4V Alloy via Annealing Heat Treatment

by Di Wang, Han Wang, Xiaojun Chen, Yang Liu, Dong Lu, Xinyu Liu and Changjun Han

Micromachines 2022, 13(2), 331; https://doi.org/10.3390/mi13020331 - 19 Feb 2022

Cited by 11 | Viewed by 2493

Abstract

This work investigated the influence of process parameters on the densification, microstructure, and mechanical properties of a Ti–6Al–4V alloy printed by selective laser melting (SLM), followed by annealing heat treatment. In particular, the evolution mechanisms of the microstructure and mechanical properties of the [...] Read more.

This work investigated the influence of process parameters on the densification, microstructure, and mechanical properties of a Ti–6Al–4V alloy printed by selective laser melting (SLM), followed by annealing heat treatment. In particular, the evolution mechanisms of the microstructure and mechanical properties of the printed alloy with respect to the annealing temperature near the β phase transition temperature were investigated. The process parameter optimization of SLM can lead to the densification of the printed Ti–6Al–4V alloy with a relative density of 99.51%, accompanied by an ultimate tensile strength of 1204 MPa and elongation of 7.8%. The results show that the microstructure can be tailored by altering the scanning speed and annealing temperature. The SLM-printed Ti–6Al–4V alloy contains epitaxial growth β columnar grains and internal acicular martensitic α′ grains, and the width of the β columnar grain decreases with an increase in the scanning speed. Comparatively, the printed alloy after annealing in the range of 750–1050 °C obtains the microstructure consisting of α + β dual phases. In particular, network and Widmanstätten structures are formed at the annealing temperatures of 850 °C and 1050 °C, respectively. The maximum elongation of 14% can be achieved at the annealing temperature of 950 °C, which was 79% higher than that of as-printed samples. Meanwhile, an ultimate tensile strength larger than 1000 MPa can be maintained, which still meets the application requirements of the forged Ti–6Al–4V alloy. Full article

(This article belongs to the Special Issue Laser Additive Manufacturing: Design, Materials, Processes and Applications)

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12 pages, 2285 KiB

Open AccessEditor’s ChoiceArticle

Four-Dimensional Stimuli-Responsive Hydrogels Micro-Structured via Femtosecond Laser Additive Manufacturing

by Yufeng Tao, Chengchangfeng Lu, Chunsan Deng, Jing Long, Yunpeng Ren, Zijie Dai, Zhaopeng Tong, Xuejiao Wang, Shuai Meng, Wenguang Zhang, Yinuo Xu and Linlin Zhou

Micromachines 2022, 13(1), 32; https://doi.org/10.3390/mi13010032 - 27 Dec 2021

Cited by 12 | Viewed by 3139

Abstract

Rapid fabricating and harnessing stimuli-responsive behaviors of microscale bio-compatible hydrogels are of great interest to the emerging micro-mechanics, drug delivery, artificial scaffolds, nano-robotics, and lab chips. Herein, we demonstrate a novel femtosecond laser additive manufacturing process with smart materials for soft interactive hydrogel [...] Read more.

Rapid fabricating and harnessing stimuli-responsive behaviors of microscale bio-compatible hydrogels are of great interest to the emerging micro-mechanics, drug delivery, artificial scaffolds, nano-robotics, and lab chips. Herein, we demonstrate a novel femtosecond laser additive manufacturing process with smart materials for soft interactive hydrogel micro-machines. Bio-compatible hyaluronic acid methacryloyl was polymerized with hydrophilic diacrylate into an absorbent hydrogel matrix under a tight topological control through a 532 nm green femtosecond laser beam. The proposed hetero-scanning strategy modifies the hierarchical polymeric degrees inside the hydrogel matrix, leading to a controllable surface tension mismatch. Strikingly, these programmable stimuli-responsive matrices mechanized hydrogels into robotic applications at the micro/nanoscale (<300 × 300 × 100 μm³). Reverse high-freedom shape mutations of diversified microstructures were created from simple initial shapes and identified without evident fatigue. We further confirmed the biocompatibility, cell adhesion, and tunable mechanics of the as-prepared hydrogels. Benefiting from the high-efficiency two-photon polymerization (TPP), nanometer feature size (<200 nm), and flexible digitalized modeling technique, many more micro/nanoscale hydrogel robots or machines have become obtainable in respect of future interdisciplinary applications. Full article

(This article belongs to the Special Issue Laser Additive Manufacturing: Design, Materials, Processes and Applications)

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20 pages, 7135 KiB

Open AccessEditor’s ChoiceArticle

A Layer-Dependent Analytical Model for Printability Assessment of Additive Manufacturing Copper/Steel Multi-Material Components by Directed Energy Deposition

by Wenqi Zhang, Baopeng Zhang, Haifeng Xiao, Huanqing Yang, Yun Wang and Haihong Zhu

Micromachines 2021, 12(11), 1394; https://doi.org/10.3390/mi12111394 - 13 Nov 2021

Cited by 7 | Viewed by 1802

Abstract

Copper/steel bimetal, one of the most popular and typical multi-material components (MMC), processes excellent comprehensive properties with the high strength of steel and the high thermal conductivity of copper alloy. Additive manufacturing (AM) technology is characterized by layer-wise fabrication, and thus is especially [...] Read more.

Copper/steel bimetal, one of the most popular and typical multi-material components (MMC), processes excellent comprehensive properties with the high strength of steel and the high thermal conductivity of copper alloy. Additive manufacturing (AM) technology is characterized by layer-wise fabrication, and thus is especially suitable for fabricating MMC. However, considering both the great difference in thermophysical properties between copper and steel and the layer-based fabrication character of the AM process, the optimal processing parameters will vary throughout the deposition process. In this paper, we propose an analytical calculation model to predict the layer-dependent processing parameters when fabricating the 07Cr15Ni5 steel on the CuCr substrate at the fixed layer thickness (0.3 mm) and hatching space (0.3 mm). Specifically, the changes in effective thermal conductivity and specific heat capacity with the layer number, as well as the absorption rate and catchment efficiency with the processing parameters are considered. The parameter maps predicted by the model have good agreement with the experimental results. The proposed analytical model provides new guidance to determine the processing windows for novel multi-material components, especially for the multi-materials whose physical properties are significantly different. Full article

(This article belongs to the Special Issue Laser Additive Manufacturing: Design, Materials, Processes and Applications)

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12 pages, 7277 KiB

Open AccessArticle

Laser-Sintered Mg-Zn Supersaturated Solid Solution with High Corrosion Resistance

by Youwen Yang, Wei Wang, Mingli Yang, Yingxin Yang, Dongsheng Wang, Zhigang Liu and Cijun Shuai

Micromachines 2021, 12(11), 1368; https://doi.org/10.3390/mi12111368 - 06 Nov 2021

Cited by 7 | Viewed by 1881

Abstract

Solid solutions of Zn as an alloy element in Mg matrixes are expected to show improved corrosion resistance due to the electrode potential being positively shifted. In this study, a supersaturated solid solution of Mg-Zn alloy was achieved using mechanical alloying (MA) combined [...] Read more.

Solid solutions of Zn as an alloy element in Mg matrixes are expected to show improved corrosion resistance due to the electrode potential being positively shifted. In this study, a supersaturated solid solution of Mg-Zn alloy was achieved using mechanical alloying (MA) combined with laser sintering. In detail, supersaturated solid solution Mg-Zn powders were firstly prepared using MA, as it was able to break through the limit of phase diagram under the action of forced mechanical impact. Then, the alloyed Mg-Zn powders were shaped into parts using laser sintering, during which the limited liquid phase and short cooling time maintained the supersaturated solid solution. The Mg-Zn alloy derived from the as-milled powders for 30 h presented enhanced corrosion potential and consequently a reduced corrosion rate of 0.54 mm/year. Cell toxicity tests confirmed that the Mg-Zn solid solution possessed good cytocompatibility for potential clinical applications. This study offers a new strategy for fabricating Mg-Zn solid solutions using laser sintering with MA. Full article

(This article belongs to the Special Issue Laser Additive Manufacturing: Design, Materials, Processes and Applications)

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Review

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41 pages, 14677 KiB

Open AccessFeature PaperEditor’s ChoiceReview

A Review of Spatter in Laser Powder Bed Fusion Additive Manufacturing: In Situ Detection, Generation, Effects, and Countermeasures

by Zheng Li, Hao Li, Jie Yin, Yan Li, Zhenguo Nie, Xiangyou Li, Deyong You, Kai Guan, Wei Duan, Longchao Cao, Dengzhi Wang, Linda Ke, Yang Liu, Ping Zhao, Lin Wang, Kunpeng Zhu, Zhengwen Zhang, Liang Gao and Liang Hao

Micromachines 2022, 13(8), 1366; https://doi.org/10.3390/mi13081366 - 22 Aug 2022

Cited by 53 | Viewed by 7512

Abstract

Spatter is an inherent, unpreventable, and undesired phenomenon in laser powder bed fusion (L-PBF) additive manufacturing. Spatter behavior has an intrinsic correlation with the forming quality in L-PBF because it leads to metallurgical defects and the degradation of mechanical properties. This impact becomes [...] Read more.

Spatter is an inherent, unpreventable, and undesired phenomenon in laser powder bed fusion (L-PBF) additive manufacturing. Spatter behavior has an intrinsic correlation with the forming quality in L-PBF because it leads to metallurgical defects and the degradation of mechanical properties. This impact becomes more severe in the fabrication of large-sized parts during the multi-laser L-PBF process. Therefore, investigations of spatter generation and countermeasures have become more urgent. Although much research has provided insights into the melt pool, microstructure, and mechanical property, reviews of spatter in L-PBF are still limited. This work reviews the literature on the in situ detection, generation, effects, and countermeasures of spatter in L-PBF. It is expected to pave the way towards a novel generation of highly efficient and intelligent L-PBF systems. Full article

(This article belongs to the Special Issue Laser Additive Manufacturing: Design, Materials, Processes and Applications)

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20 pages, 5931 KiB

Open AccessReview

A Review on Macroscopic and Microstructural Features of Metallic Coating Created by Pulsed Laser Material Deposition

by Xinlin Wang, Jinkun Jiang and Yongchang Tian

Micromachines 2022, 13(5), 659; https://doi.org/10.3390/mi13050659 - 22 Apr 2022

Cited by 14 | Viewed by 1999

Abstract

Owing to the unparalleled advantages in repairing of high value-add component with big size, fabricating of functionally graded material, and cladding to enhance the surface properties of parts, the laser material deposition (LMD) is widely used. Compared to the continuous wave (CW) laser, [...] Read more.

Owing to the unparalleled advantages in repairing of high value-add component with big size, fabricating of functionally graded material, and cladding to enhance the surface properties of parts, the laser material deposition (LMD) is widely used. Compared to the continuous wave (CW) laser, the controllability of the laser energy would be improved and the temperature history would be different under the condition of pulse wave (PW) laser through changing the pulse parameters, such as duty cycle and pulse frequency. In this paper, the research status of temperature field simulation, surface quality, microstructural features, including microstructures, microhardness, residual stress, and cracking, as well as corrosion behavior of metallic coating created by pulsed laser material deposition have been reviewed. Furthermore, the existing knowledge and technology gaps are identified while the future research directions are also discussed. Full article

(This article belongs to the Special Issue Laser Additive Manufacturing: Design, Materials, Processes and Applications)

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