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Journal of Materials Science & Technology 2022年第26期121卷 163-173页

作者： Bingqian Jin Nannan Zhang Shuo Yin Department of Material Science and Engineering Shenyang University of TechnologyShenyang 110870China Department of Mechanical Manufacturing and Biomedical EngineeringTrinity College DublinThe University of DublinParsons BuildingDublin 2Ireland

High-entropy alloy(HEA)coatings are of great importance in the fabrication of wear resistance materials.HEA coatings containing ceramic particles as reinforcement phase usually have better wear performance.In this study,AlCoCrFe Ni(TiN)_(x)(x:molar ratio;x=0,0.2,0.4,0.6,0.8,1.0)HEA coatings were fabricated on Q235 steel by plasma spray first and then subjected to laser remelting.The experimental results confirm that plasma spray together with post laser remelting could result in the in-situ formation of TiN-Al_(2)O_(3) ceramic particles and cuboidal B2 phase in the AlCoCrFeNi(TiN)_(x) HEA coatings.The in-situ TiN-Al_(2)O_(3) and nano-cuboidal B2 precipitation phase strengthened the coatings and improved their wearresistance properties.Due to the dispersion of hard phase and nano-particles resulting from second heating,the microhardness of the Al Co Cr Fe Ni(Ti N)coatings significantly increased from 493 to 851 HV after laser remelting.For the same reasons,the wear-resistance performance was also significantly promoted after laser remelting.

关键词： High-entropy alloy Coatings Ceramics laser remelting Microstructure Wear resistance

The crystallographic texture and dependent mechanical properties of the CrCoNi medium-entropy alloy by laser remelting strategy

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Journal of Materials Science & Technology 2022年第16期111卷 245-255页

作者： Pengsheng Xue Lida Zhu Jinsheng Ning Peihua Xu Shuhao Wang Zhichao Yang Yuan Ren Guiru Meng School of Mechanical Engineering and Automation Northeastern UniversityShenyang 110819China State Key Laboratory for Mechanical Behavior of Materials School of Materials Science and EngineeringXi’an Jiaotong UniversityXi’an 710049China

laser remelting(LR)has attracted widespread attention in recent years as an effective method to reduce internal defects and improve the surface quality of additively manufactured(AM)parts.In the present study,three different LR inter-layer scanning strategies(LR0,LR90 and LR45)and their effects on the porosity,microstructure,crystallographic texture and related mechanical properties of parts have been studied.Optical microscope,X-ray diffraction,and scanning electron microscope were used as characterization tools.In the LR90 sample,it shows obvious{111}texture and strongpreferred orientation along the scanning direction(SD),while the 0°offset and the 45°rotation of LR scanning strategy form a finer microstructure and weak crystallographic texture.Meanwhile,the mechanical properties of the LR sample are improved compared with the sample only by laser metal deposition(LMD),and a combination of higher strength and optimal uniform elongation is obtained in the LR45 sample.The overall results show that a reasonable LR scanning strategy can reduce the anisotropy of AM parts and improve their mechanical properties.

关键词： CrCoNi laser remelting Porosity Crystallographic orientation Mechanical properties

Refined microstructure and enhanced mechanical properties of AlCrFe_(2)Ni_(2) medium entropy alloy produced via laser remelting

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Journal of Materials Science & Technology 2022年第4期99卷 18-27页

作者： Tianyi Han Yong Liu Mingqing Liao Danni Yang Nan Qu Zhonghong Lai Jingchuan Zhu School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China National Key Laboratory for Precision Hot Processing of Metals Harbin Institute of TechnologyHarbin 150001China Center of Analysis and Measurement and Computing Harbin Institute of TechnologyHarbin 150001China

A Co-free as-cast AlCrAlCrFe_(2)Ni_(2)medium entropy alloy(MEA)with multi-phases was remelted by fiber laser in this study.The effect of laser remelting on the microstructure,phase distribution and mechanical properties was investigated by characterizing the as-cast and the remelted AlCrAlCrFe_(2)Ni_(2)alloy.The laser remelting process resulted in a significant decrease of grain size from about 780μm to 58.89μm(longitudinal section)and 15.87μm(transverse section)and an increase of hardness from 4.72±0.293 GPa to 6.40±0.147 GPa(longitudinal section)and 7.55±0.360 GPa(transverse section).It was also found that the long side plate-like microstructure composed of FCC phase,ordered B2 phase and disordered BCC phase in the as-cast alloy was transformed into nano-size weave-like microstructure consisting of alternating ordered B2 and disordered BCC phases.The mechanical properties were evaluated by the derived stressstrain relationship obtained from nano-indentation tests data.The results showed that the yield stress increased from 661.9 MPa to 1347.6 MPa(longitudinal section)and 1647.2 MPa(transverse section)after remelting.The individual contribution of four potential strengthening mechanisms to the yield strength of the remelted alloy was quantitatively evaluated,including grain boundary strengthening,dislocation strengthening,solid solution strengthening and precipitation strengthening.The calculation results indicated that dislocation and precipitation are dominant strengthening mechanisms in the laser remelted MEA.

关键词： Medium entropy alloy laser remelting Microstructure Nano-indentation Strengthening mechanism

On the Martensitic Transformation Temperatures and Mechanical Properties of NiTi Alloy Manufactured by Selective laser Melting: Effect of remelting

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Acta Metallurgica Sinica(English Letters) 2021年第9期34卷 1223-1233页

作者： Jian-Bin Zhan Yan-Jin Lu Jin-Xin Lin College of Chemistry and Materials Science Fujian Normal UniversityFuzhou 350007China Key Laboratory of Optoelectronic Materials Chemistry and Physics Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002China

In this study, the infl uence of laser remelting on the relative density, martensitic transformation temperatures(MTTs), and mechanical properties of a NiTi alloy fabricated by selective laser melting(SLM) at a laser power between 15 and 75 W were investigated. A relative alloy density of approximately 99% was achieved in the power range of 45–60 W corresponding to the forming energy density range of 65.45–87.27 J/mm3. The MTTs increased with the increase in the energy density;thus, the initial contents of the B2 and B19′ phases of the SLM-produced NiTi alloy can be tailored by the utilized technique. However, the number of defects such as metallurgical pores and microcracks considerably increased at higher energy densities(> 87.27 J/mm3). Interestingly, the concentration of these defects was reduced by remelting in the energy density range of 21.82–65.45 J/mm3, while the alloy relative density increased to 99.7% ± 0.1% at a remelting energy density of 65.45 J/mm3. The results of tensile testing revealed that when the remelting energy was 75% or 100% of the forming energy input, the ultimate tensile strength and elongation of the alloy significantly increased. Therefore, the remelting strategy represents a promising route for manufacturing NiTi alloys with desired MTT ranges and mechanical properties.

关键词： Selective laser melting NiTi alloy laser remelting Martensitic transformation temperature

Microstructure and properties of hybrid additive manufacturing 316L component by directed energy deposition and laser remelting

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Journal of Iron and Steel Research(International) 2020年第7期27卷 842-848页

作者： Xiao-hui Chen Bo Chen Xu Cheng Guo-chao Li Zheng Huang National Engineering Laboratory of Additive Manufacturing for Large Metallic Components and Engineering Research CenterMinistry of Education on Laser Direct Manufacturing for Large Metallic ComponentsSchool of Materials Science and EngineeringBeihang UniversityBeijing 100191China Research Center for Processing AECC Shanghai Commercial Aircraft Engine Manufacturing Co.Ltd.Shanghai 201306China

Arc additive manufacturing is a high-productivity and low-cost technology for directly fabricating fully dense metallic components.However,this technology with high deposit rate would cause degradation of dimensional accuracy and surface quality of the metallic component.A novel hybrid additive manufacturing technology by combining the benefit of directed energy deposition and laser remelting is developed.This hybrid technology is successfully utilized to fabricate 316L component with excellent surface quality.Results show that laser remelting can largely increase the amount ofδphases and eliminateσphases in additive manufacturing 316L component surface due to the rapid cooling.This leads to the formation of remelting layer with higher microhardness and excellent corrosion resistance when compared to the steel made by directed energy deposition only.Increasing laser remelting power can improve surface quality as well as corrosion resistance,but degrade microhardness of remelting layer owing to the decrease inδphases.

关键词： Hybrid additive manufacturing laser remelting Directed energy deposition Microstructure Corrosion resistance

Effect of laser remelting on the Microstructure and Corrosion Resistance of Plasma Sprayed Fe-based Coating

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Journal of Wuhan University of Technology(Materials Science) 2015年第4期30卷 804-807页

作者：姜超平 WANG Junxing HAN Jianjun LU Yuan XING Yazhe CHEN Yongnan SONG Xuding School of Materials Science and Engineering Chang'an University Key Laboratory of Road Construction Technology and Equipment MOE Chang'an University Xi'an Special Equipment Inspection Institute

Fe-based amorphous and nanocrystalline coatings were fabricated by air plasma spraying. The coatings were further treated by laser remelting process to improve their microstructure and properties. The corrosion resistance of the as-sprayed and laser-remelted coatings in 3.5wt% NaC1 and 1 mol/L HCI solutions was evaluated by electrochemical polarization analysis. It was found that laser-remelted coating appeared much denser than the as-sprayed coating. However, laser-remelted coating contains much more nanocrystalline grains than the as-sprayed coatings, resulting from the lower cooling rate in laser remelting process compared with plasma spraying process. Electrochemical polarization results indicated that the laser-remelted coating has great corrosion resistance than the as-sprayed coating because of its dense structure.

关键词： plasma spraying coating laser remelting corrosion

Microstructures and properties of Fe-Co-B-Si-Nb coating prepared by laser cladding and remelting

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China Welding 2011年第1期20卷 54-58页

作者：朱彦彦黄坚李铸国李瑞峰 Shanghai Key Laboratory of Materials laser Processing and Modification School of Materials Science and Engineering Shanghai Jiao Tong University Shanghai 200240

High power laser cladding of [ （ Fe0. 5 Co0. 5 ） 0. 75 B0. 2 Si0.05 ] 95. 7 Nb4. 3 powder mixture afier-remelting was performed to fabricate Fe-based metallic glass coating on the surface of steel of China Classification Society： Grade B （CCS-B）. Scanning electron microscopy （SEM）, X-ray diffraction （XRD）, transmission electron microscopy （TEM） with energy dispersive spectrometer （EDS）, Vickers hardness tester and corrosion resistance tester were employed to characterize microstructures and evaluate properties of this coating. According to the results of SEM, XRD and TEM, the cladding coating consisted of nanocrystalline embedded in amorphous phase. EDS data indicated that Nb segregated in the amorphous matrix. The results of hardness test revealed that the hardness of the top layer was higher than that of the inner layer of the coating. The coating exhibited excellent corrosion resistance in a 3.5% NaCl solution.

关键词： laser cladding laser remelting amorphous metallic coating microstructure

Effect of laser remelting on microstructure and mechanical properties of CrMnFeCoNi high entropy alloy

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China Welding 2021年第2期30卷 1-10页

作者：郭伟蔡艳 Shanghai Key Laboratory of Materials laser Processing and Modification Shanghai Jiao Tong UniversityShanghai 200240China Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration Shanghai 200240China

Equiatomic CrMnFeCoNi high entropy alloy prepared by powder metallurgy was remelted by laser.The relative density and microstructure of fusion zone are evaluated.The nanoindentation tests are conducted to reveal the hardness difference of dendrite arms and interdendritic areas.Tensile tests are conducted to assess the mechanical properties of remelted HEA.After laser remelting,the number and morphology of voids changed significantly.Dendritic structure with face-centered cubic phase form in the fusion zone.Fe,Cr and Co are enriched in dendrite arm,while Mn and Ni are enriched in interdendritic area.Elements segregation led to a nanohardness difference between dendrite arm and interdendritic area.Local deformation occurs in interdendritic area during tensile tests and results in a fracture with directionality.

关键词： high-entropy alloy powder metallurgy laser remelting dendritic segregation nano-indentation

In Situ Elimination of Pores During laser Powder Bed Fusion of Ti–6.5Al–3.5Mo–l.5Zr–0.3Si Titanium Alloy

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Acta Metallurgica Sinica(English Letters) 2022年第3期35卷 439-452页

作者： Ling Zhang Wen-He Liao Ting-Ting Liu Hui-Liang Wei Chang-Chun Zhang School of Mechanical Engineering Nanjing University of Science and TechnologyNanjing 210094.China

The printing quality of components manufactured using laser powder bed fusion(LPBF)generally depends on the presence of various defects such as massive porosity.Thus,the efficient elimination of pores is an important factor in the production of a sound LPBF product.In this study,the efficacy of two in situ laser remelting approaches to eliminating pores during the LPBF of a titanium alloy Ti–6.5 Al–3.5 Mo–l.5 Zr–0.3 Si(TC11)was assessed both experimentally and computationally.These two remelting methods are surface remelting and layer-by-layer printing and remelting.A multi-track multi-layer phenomenological model was established to analyze the variation of pores with the temperature and velocity fields.The results showed that surface remelting with a high laser power,such as 180 W,can eff ectively eliminate pores within three deposited layers.However,such remelting could not reach defects in deeper regions.Layer-by-layer remelting with a 180 W laser could eff ectively eliminate the pores formed in the previous layer in real time.The results obtained in this study can provide useful guidance for the in situ control of printing defects supported by real-time monitoring,feedback,and operating systems of an intelligent LPBF equipment.

关键词： laser powder bed fusion Ti–6.5Al–3.5Mo–l.5Zr–0.3Si Pores laser remelting

Effects of substrate surface treatments on hybrid manufacturing of AlSi7Mg using die casting and selective laser melting

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Journal of Materials Science & Technology 2023年第25期156卷 142-156页

作者： Haiyang Fan Ann Witvrouw Friedrich Wolf-Monheim Rainer Souschek Shoufeng Yang Department of Mechanical Engineering and Flanders Make KU LeuvenCelestijnenlaan 300Bbox 2420HeverleeB-3001 LeuvenBelgium Ford Research & Advanced Engineering Ford Research and Innovation Center AachenSüsterfeldstraße 20052072 AachenGermany Yantai Research Institute Harbin Engineering University264000 YantaiChina

To balance the manufacturing cost and customizability of automotive parts,a hybrid manufacturing process combining die-casting and selective laser melting(SLM)is proposed:starting with a conventional cast substrate,SLM is utilized to add additional geometric elements on top of it.For this hybrid process,the first priority is to prepare a substrate surface suitable for the subsequent SLM addition of the top-on elements.In this study,the original cast surface of AlSi7Mg was processed by sandblasting,wire electro-discharge machining,and laser remelting,respectively.Then,additional AlSi7Mg components were built on both the original cast and treated surfaces through SLM.After hybrid builds,these surfaces and resultant interfaces were examined by optical and scanning electron microscopes.Results indicate that the defect-free metallurgical joint between the cast and additively added parts can be formed on all surfaces except for the one processed by electro-discharge machining.The observed epitaxial grain growth crossing the interface implies a strong connection between the cast and the SLMed component.Despite these benefits,also mismatches in microstructure,residual stress level and element distribution between the two parts are identified.After a comprehensive assessment,laser remelting with no additional machining is recommended as the optimal surface treatment preceding SLM fabrication,because of its user-friendly operation,low cost,and high industrial feasibility.

关键词： Hybrid manufacturing Aluminium alloy Surface treatment laser remelting Interface Automotive