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Application of Synchrotron X-Ray Imaging and Diffraction in Additive Manufacturing:A Review

Acta Metallurgica Sinica(English Letters) 2022年第1期35卷 25-48页

作者： Naying An sansan shuai Tao Hu Chaoyue Chen Jiang Wang Zhongming Ren State Key Laboratory of Advanced Special Steels School of Materials Science and EngineeringShanghai UniversityShanghai200444China

Additive manufacturing(AM)is a rapid prototyping technology based on the idea of discrete accumulation which off ers an advantage of economically fabricating a component with complex geometries in a rapid design-to-manufacture cycle.However,various internal defects,such as balling,cracks,residual stress and porosity,are inevitably occurred during AM due to the complexity of laser/electron beam-powder interaction,rapid melting and solidification process,and microstructure evolution.The existence of porosity defects can potentially deteriorate the mechanical properties of selective laser melting(SLM)components,such as material stiff ness,hardness,tensile strength,and fatigue resistance performance.Synchrotron X-ray imaging and diffraction are important non-destructive means to elaborately characterize the internal defect characteristics and mechanical properties of AM parts.This paper presents a review on the application of synchrotron X-ray in identifying and verifying the quality and requirement of AM parts.Defects,microstructures and mechanical properties of printed components characterized by synchrotron X-ray imaging and diffraction are summarized in this review.Subsequently,this paper also elaborates on the online characterization of the evolution of the microstructure during AM using synchrotron X-ray imaging,and introduces the method for measuring AM stress by X-ray diffraction(XRD).Finally,the future application of synchrotron X-ray characterization in the AM is prospected.

关键词： Additive manufacturing Synchrotron X-ray imaging X-ray diffraction Defect formation Mechanical properties Residual stress

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Selective Laser Melting of Carbon-Free Mar-M509 Co-Based Superalloy:Microstructure,Micro-Cracks,and Mechanical Anisotropy

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Acta Metallurgica Sinica(English Letters) 2022年第3期35卷 501-516页

作者： Xiaodong Wang Chaoyue Chen Ruixin Zhao Longtao Liu sansan shuai Tao Hu Jiang Wang Zhongming Ren State Key Laboratory of Advanced Special Steels School of Materials Science and EngineeringShanghai UniversityShanghai 200444.China

In this work,the microstructural evolution,micro-crack formation,and mechanical anisotropy of the selective laser melted(SLM)carbon-free Mar-M509 Co-based superalloy were systematically studied under different linear energy densities(LED).Observation shows that the SLM Mar-M509 superalloy possesses a fully dense structure,whereas some microcracks exist along the building direction.The electron backscatter diffraction results reveal that dominant columnar grains tend to elongate along the building direction parallel to the XZ plane.Meanwhile,both anear fiber texture and a{100}near sheet texture are observed in different specimens.For the specimen with fiber texture,a high misorientation angle exists among different columnar grains,which aggravated the generation of micro-cracks under thermal stress.Higher LED results in higher micro-crack density in the SLM specimen due to higher thermal stress.Mar-M509 specimen fabricated under lower LED exhibits higher tensile strength due to more significant grain refinement.More prominent anisotropy of tensile performance was found in the high LED specimen,which can be attributed to the higher density of micro-cracks and crystallographic texture.Furthermore,the SLM Mar-M509 superalloy exhibits better mechanical properties than the traditional cast technique.In summary,this work can contribute to the development and the future application of SLM-fabricated Co-based superalloy.

关键词： Selective laser melting Mar-M509 Co-based superalloy Linear energy density Anisotropy Mechanical properties

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Microstructure and mechanical properties of directionally solidified Al-rich Ni_(3)Al-based alloy under static magnetic field

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Journal of Materials Science & Technology 2022年第15期110卷 117-127页

作者： Xin Liu sansan shuai Chenglin Huang Shijun Wu Tao Hu Chaoyue Chen Jiang Wang Zhongming Ren State Key Laboratory of Advanced Special Steels School of Materials Science and EngineeringShanghai UniversityShanghai 200444China

The influence of a longitudinal static magnetic field on microstructures and mechanical properties of Ni_(3)Al-based alloy during directional solidification at the growth speed of 25μm/s and 100μm/s has been experimentally investigated.Results reflected that the utilization of a 0.5 T magnetic field refines the Ni Al dendrites at both speeds of growth.When applying a high magnetic field,the columnar-to-equiaxed transition(CET)occurred at growth speed of 25μm/s and dendrite networks formed at growth speed of 100μm/s.Tensile property results indicated that the refinement of dendrites enhanced both plasticity and ultimate tensile strength of Ni-Al alloy.The change of microstructures and mechanical properties should be attributed to the combined action of the thermoelectric magnetic convection(TEMC)in mushy zone together with the thermoelectric magnetic force(TEMF)acting on the solid.When applying a low magnetic field(0.5 T),the TEMF is too small to fragment the dendrites,and the refined dendrites is mainly due to the TEMC in the interdendritic regions.At a lower growth speed,the TEMF is supposed to strong enough to fragment the dendrites and induce the occurrence of CET under 2 or 4 T.When the growth speed increased to 100μm/s,no obvious CET was observed,but a vertical secondary convection is induced by the circulation in the parallel plane,which promotes the growth of secondary and tertiary branches,leading to the formation of abnormally developed high order dendrites.The hierarchical dendritic structure was suggested to provide a channel for rapid crack propagation and thus degraded the mechanical properties.

关键词： Ni_(3)Al-based alloy Magnetic field Directional solidification Columnar to equiaxed transition Mechanical properties

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Revealing the Diversity of Dendritic Morphology Evolution During Solidification of Magnesium Alloys using Synchrotron X-ray Imaging:A Review

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Acta Metallurgica Sinica(English Letters) 2022年第2期35卷 177-200页

作者： Yanan Wang sansan shuai Chenglin Huang Tao Jing Chaoyue Chen Tao Hu Jiang Wang Zhongming Ren State Key Laboratory of Advanced Special Steels School of Materials Science and EngineeringShanghai UniversityShanghai 200444China School of Materials Tsinghua UniversityBeijing 10084China

In this paper,the diversity of complicated dendrite microstructure and its evolution behavior during solidification in different magnesium alloys under various processing conditions were illustrated using synchrotron X-ray imaging technique.A variety of dendritic morphologies and branching structures were revealed,i.e.,sixfold plate-like symmetric structure in Mg-Al-based structure,12-branch structure in Mg-Zn-based alloys and 18-branch structure in Mg-Sn-and Mg-Ca-based alloys as well as seaweed like hyper-branched structure in Mg-38wt%Zn alloy.In addition,a dendrite morphology and orientation transition with increasing addition of Zn content were also observed in Mg-Zn alloy,with dendrite growth pattern transform from anisotropy(low Zn addition)with sixfold symmetric snow-flake structure to relative isotropy(intermediate Zn addition)where seaweed morphology presented and then back to anisotropy(high Zn addition)when only 12 branches with preferredorientations were observed.The phase-field model representing the typical dendritic morphologies and branching structures under various conditions was also depicted and discussed.Further,the two-dimensional(2D)real-time dendrite growth dynamics in different Mg-based alloys captured using synchrotron X-ray radiography for unveiling the originate of theα-Mg dendrite was reviewed.Following this,the four-dimensional(3D+time)synchrotron X-ray tomographic in situ observation of dendritic morphology evolution indicating the formation mechanism of the diverse dendritic morphology during Mg-Sn-and Mg-Zn-based alloys was also summarized.Finally,the future study on exploring the complicated dendritic morphologies and their origination during solidification of Mg-based alloys is prospected.

关键词： Magnesium alloys Solidification microstructure Dendritic morphology Synchrotron X-ray imaging Growth pattern

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Three dimensional dendritic morphology and orientation transition induced by high static magnetic field in directionally solidified Al-10wt.%Zn alloy

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Journal of Materials Science & Technology 2019年第8期35卷 1587-1592页

作者： sansan shuai Xin Lin Yuanhao Dong Long Hou Hanlin Liao Jiang Wang Zhongming Ren State Key Laboratory of Advanced Special Steel School of Materials Science and EngineeringShanghai UniversityShanghai 200444 China State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi'an 710072 China Université de Technologie de Belfort-Montbéliard LERMPS Site de Sévenans90010 Belfort Cedex France

Effect of high static magnetic field on the dendritic morphology and growth direction in directionally solidified Al-10 wt.%Zn alloy were studied by three-dimensional(3D) X-ray micro-computed tomography, Electron Back-scattered Diffraction(EBSD) and X-ray Diffraction(XRD). The application of high static axial magnetic field(5T) during directional solidification was found to destabilize the solid/liquid interface and cause the growth direction of dendrite deviate from thermal gradient, leading to irregular solid/liquid interfacial shape and cellular to dendritic morphology transition. The thermoelectric magnetic convection(TEMC) caused by the interaction of thermoelectric effect and magnetic field was supposed to be responsible for the transition. In addition, the EBSD and XRD results confirm that the preferred growth direction of α-Al was found to transform from the traditionally expected to. The dendrite orientation transition(DOT) in Al-10 wt.%Zn alloy can be attributed to the effect of applied magnetic field on the anisotropy of crystal during solidification. The result indicates the potential application of high static magnetic field in altering the morphology and preferred growth direction of dendrite during directional solidification.

关键词： Al-Zn alloy High static magnetic field Three-dimensional dendrite morphology Dendrite orientation transition X-ray computed tomography

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In-situ observation of solid-liquid interface transition during directional solidification of Al-Zn alloy via X-ray imaging

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Journal of Materials Science & Technology 2020年第4期39卷 113-123页

作者： Yuanhao Dong sansan shuai Tianxiang Zheng Jiawei Cao Chaoyue Chen Jiang Wang Zhongming Ren State Key Laboratory of Advanced Special Steel School of Materials Science and EngineeringShanghai UniversityShanghai 200444China

The morphological instability of solid/liquid(S/L)interface during solidification will result in different patterns of microstructure.In this study,two dimension(2 D)and three dimension(3 D)in-situ observation of solid/liquid interfacial morphology transition in Al-Zn alloy during directional solidification were performed via X-ray imaging.Under a condition of increasing temperature gradient(G),the interface transition from dendritic pattern to cellular pattern,and then to planar growth with perturbation was captured.The effect of solidification parameter(the ratio of temperature gradient and growth velocity(v),G/v)on morphological instabilities was investigated and the experimental results were compared to classical"constitutional supercooling"theory.The results indicate that 2 D and 3 D evolution process of S/L interface morphology under the same thermal condition are different.It seems that the S/L interface in 2 D observation is easier to achieve planar growth than that in 3 D,implying higher S/L interface stability in 2 D thin plate samples.This can be explained as the restricted liquid flow under 2 D solidification which is beneficial to S/L interface stability.The in-situ observation in present study can provide coherent dataset for microstructural formation investigation and related model validation during solidification.

关键词： Al-Zn alloy Directional solidification Solid/liquid interface instability In-situ observation X-ray imaging

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Revealing the influence of high magnetic field on the solute distribution during directional solidification of Al-Cu alloy

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Journal of Materials Science & Technology 2021年第29期88卷 226-232页

作者： Pengchuan Wang sansan shuai Chenglin Huang Xin Liu Yanan Fu Jiang Wang Zhongming Ren State Key Laboratory of Advanced Special Steels School of Materials Science and EngineeringShanghai UniversityShanghai200444China Shanghai Synchrotron X-ray Facility Shanghai Institute of Applied PhysicsCASShanghai201204China

The effect of the high magnetic field(MF)on the distribution of solute concentration during directional solidification of Al-Cu alloy under low growth speed was experimentally investigated.The amount of nonequilibrium eutectic is quantified via X-ray computed tomography(XCT)and demonstrated to reduce with the application of MF.Further,experimental results reveal that the MF alleviates the microsegregation and increases the average Cu concentration in solid solution,leading to the increases of the effective partition coefficient ke.It was also found that Cu concentration in solid solution increases continuously with the increasing intensity of MF,following the strengthening of micro-hardness.The change of ke under the MF is demonstrated to attribute to the thermoelectric magnetic convection(TEMC)in the mushy zone and the thermoelectric magnetic force(TEMF)acting on the solid.The TEMC is supposed to cause secondary convection owing to the inequality in flow velocities of circulation in different positions of dendrite stem.And the vacancies created by the proliferation and movement of dislocations induced by TEMF in the matrix is supposed to be able to capture solute atoms and thus enhance the solute concentration in the solid solution.

关键词： Microsegregation Cu concentration Partition coefficient Magnetic field Directional solidification

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Effect of substrate cooling on the epitaxial growth of Ni-based single-crystal superalloy fabricated by direct energy deposition

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Journal of Materials Science & Technology 2021年第3期62卷 148-161页

作者： Jianwen Nie Chaoyue Chen Longtao Liu Xiaodong Wang Ruixin Zhao sansan shuai Jiang Wang Zhongming Ren State Key Laboratory of Advanced Special Steels School of Materials Science and EngineeringShanghai UniversityShanghai 200444China

The columnar-to-equiaxed transition(CET)or the formation of stray grains in the laser melting deposition is the least desirable for the repair of single-crystal blades.In this work,the forced water-cooling was conducted on a single-crystal Rene N5 substrate during the direct energy deposition(DED).The single track remelting,one-layer,two-layer,and eight-layer depositions were investigated to explore the grain growth mechanism.The solidification conditions of the DED process,including temperature field,temperature gradient,and solidification speed,were numerically analyzed by a finite element model.The single-track remelting results showed that the fraction of columnar crystal regions increases from55.81%in the air-cooled sample to 77.14%in the water-cooled one.The single-track deposits of one-and two-layer have the same trend,where the proportion of columnar crystal height was higher under the forced water-cooled condition.The electron backscattered diffraction(EBSD)grain-structure maps of an eight-layer deposit show that the epitaxial growth height increases from 1 mm in the air-cooling sample to 1.5 mm in the water-cooling one.The numerical results showed that the tempe rature gradient in[0011 direction was significantly increased by using forced water-cooling.In conclusion,the in-situ substrate cooling can become a potential method to promote epitaxial growth during DED via the influence on CET occurrence.

关键词： Direct energy deposition Epitaxial growth Columnar-to-equiaxed transition(CET) Temperature gradient

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X射线超快成像原位表征激光增材制造过程研究进展

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中国有色金属学报 2024年第4期34卷 1405-1427页

作者：龚来凤帅三三李雅莉黎姗姗陈超越王江任忠鸣上海大学省部共建高品质特殊钢冶金与制备国家重点实验室上海200444 上海大学材料科学与工程学院上海200444 中国航发商用航空发动机制造有限责任公司上海201306

在增材制造过程中,熔池经历快速熔化、冷却、凝固的过程,其物理、化学、结构和应力等处于极端非平衡状态,容易导致孔隙、裂纹等缺陷产生,影响制件力学性能。同步辐射X射线具有高空间分辨率和时间分辨率,可以实现增材制造过程中熔池动力... 详细信息

在增材制造过程中,熔池经历快速熔化、冷却、凝固的过程,其物理、化学、结构和应力等处于极端非平衡状态,容易导致孔隙、裂纹等缺陷产生,影响制件力学性能。同步辐射X射线具有高空间分辨率和时间分辨率,可以实现增材制造过程中熔池动力学和缺陷演化的原位表征。本文综述了近年来激光增材制造原位实验平台的搭建,并从熔池结构演化、缺陷形成机理和成形工艺优化三个方面介绍了同步辐射X射线原位表征激光增材制造过程的研究进展。最后基于目前增材制造原位观察的局限性,从表征系统改进、原料多样化和计算修正等方面对未来研究进行了展望。

关键词：同步辐射X射线超快成像激光增材制造熔池结构演化缺陷形成原理

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IN792LC单晶高温合金长期热暴露下的蠕变性能退化

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钢铁研究学报 2024年第3期36卷 359-367页

作者：李石磊帅三三汪超何磊王江任忠鸣上海大学材料科学与工程学院省部共建高品质特殊钢冶金与制备国家重点实验室上海200444 上海电气燃气轮机有限公司上海200240

研究了800℃条件下最长时间达到3 000 h的长期热暴露对IN792LC单晶高温合金显微组织演变及蠕变行为的影响。结果表明:长时间热暴露后,γ′相球化生长均匀分散在γ基体内,γ′相的粗化行为符合Lifshitz-Slyozov-Wagner(LSW)模型。热暴露... 详细信息

研究了800℃条件下最长时间达到3 000 h的长期热暴露对IN792LC单晶高温合金显微组织演变及蠕变行为的影响。结果表明:长时间热暴露后,γ′相球化生长均匀分散在γ基体内,γ′相的粗化行为符合Lifshitz-Slyozov-Wagner(LSW)模型。热暴露后一些不连续碳化物在γ/γ′共晶组织周围析出,但无拓扑密排相(TCP)生成。对长期热暴露后的合金进行了760℃/662 MPa下蠕变断裂寿命测试,随着热暴露时间延长,由于组织退化,合金蠕变寿命降低,而断裂伸长率不断提高。当热暴露达到3 000 h时,合金蠕变断裂寿命降低81.1%。合金蠕变寿命的减少主要由γ′相粗化、碳化物的退化以及柯肯达尔孔洞增大导致。分析发现在热暴露后共晶相周围MC碳化物分解形成的M_(23)C_(6)碳化物,空位在碳化物处塌陷聚集成微孔,加速了裂纹的萌生与拓展。此外,由于热暴露后合金蠕变过程中的位错网络被破坏,位错切入γ′相运动,从而进一步降低蠕变断裂寿命。研究结果为IN792LC单晶高温合金近服役温度条件下使用寿命预测提供了参考。

关键词：单晶高温合金热暴露组织退化蠕变碳化物

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