Closing the science gap in 3D metal printing

doi:10.1126/science.abb4938

GSTDTAP > 气候变化

DOI	10.1126/science.abb4938
	Closing the science gap in 3D metal printing
	Andrew T. Polonsky; Tresa M. Pollock
	2020-05-08
发表期刊	Science
出版年	2020
英文摘要	Additive manufacturing [three-dimensional (3D) printing] methodologies for high–melting point metallic materials are being used in the advanced aerospace and biomedical sectors to fabricate high-value and geometrically complex parts in moderate production volumes. One barrier to more widespread applications is the gaps in the understanding of the processes that occur during the layer-by-layer buildup by beam heating and melting of powder or wire layers. For example, the absorption of energy in powder layers that are only a few particles thick is poorly understood. On page 660 of this issue, Khairallah et al. ([ 1 ][1]) used in situ x-ray synchrotron observations of powder dynamics coupled to thermal and hydrodynamic flow modeling to study energy absorption at the scale of powder particles. The presence of the powder, relative to a flat plate without powder, improves absorptivity at low laser power, but as power approaches 200 W, the details of the powder become far less important. In powder-bed printing, overlapping linear scans or repeated spot melts with electron or laser beams in preselected patterns form a layer of the part. The process is repeated for hundreds or thousands of layers to build up an object (see the figure, left). Ideally, the print process parameters are adjusted continuously to achieve the desired material structure in zones of the printed part. In a recent demonstration, collections of small equiaxed crystals (“grains”) were printed in a background structure of large columnar crystals ([ 2 ][2]). At a macroscopic level, the power supplied by the laser, the beam shape, the scan velocity and pulse duration, and the scan pattern must be tuned to achieve favorable local melting conditions. For example, printing a simple cube 2.5 cm on each edge would typically require roughly 3 to 6 km of linear track melting, or 5 million to 30 million individual spot melts. Along this print path, the physics of laser energy absorption, powder particle motion, melting, vaporization, fluid flow, heat transfer, mass transfer of alloy constituent elements, nucleation of the solid, buildup of residual stress, and evolution of the solid-state structure of the material must be predicted and controlled to ensure reproducible printing of high-quality objects ([ 3 ][3]–[ 6 ][4]). The final properties of a material are controlled by the structure of the material derived from processing (printing) parameters as well as the size, distribution, and character of processing-induced defects. Connecting processing physics to structure and defect formation is challenging, given the complex dynamics of the powder particles. In the vicinity of the melting event, the intense heating of the powder and underlying print substrate by the laser beam creates vapor plumes that can cause particles to “recoil” away from the heated region ([ 7 ][5]). For example, a short melt track through a 50-µm-thick powder layer of a cobalt-nickel alloy ([ 8 ][6]) that was placed on top of a sheet of the same alloy can be formed (see the figure, left). The sheet is composed primarily of one large grain that exhibits continued growth through the melted layer, except in a region at the top of the melt track where new crystallites formed because of the arrival of a powder particle on the top of the melt pool. A 3D tomographic dataset ([ 9 ][7]) (see the figure, right) shows that the arrival of the powder particle results in nucleation of multiple crystals of different orientations (indicated by differences in color). The physics that produce this unusual powder particle trajectory and the implications for this disturbance in structure for the next printed layer are not well understood. Khairallah et al. studied such powder dynamics in relation to the formation of defects in stainless steel. A specific concern during printing is the ejection of “spatter,” that is, liquid droplets or entrained powder particles that undergo expulsion from the melt pool and appear as the sparks or smoke in videos of metal 3D printing. The authors observed spatter events and associated powder dynamics at high resolution during printing in a high-energy synchrotron imaging environment. To connect the observed dynamics to the physics of defect formation, Khairallah et al. modeled a “presintered” powder bed, where particles undergo preliminary fusing with their neighbors during laser-beam preheating ([ 10 ][8]). Presintered beds can reduce powder motion in electron-beam additive manufacturing but have received limited attention in process modeling. ![Figure][9] Metal-particle physics Three-dimensional printing of metal powders requires energetic laser- or electron-beam melting that can also move particles. Khairallah et al. used x-ray imaging and modeling to understand particle movement as a function of beam energy. GRAPHIC: C. BICEKL/ SCIENCE The high-resolution, multiphysics model reveals the role of spatter particles on top of the presintered bed. Khairallah et al. show several previously unknown effects that arise from the interaction of the laser beam with spatter that deposited or is in motion. Interaction of the laser beam with previously deposited spatter produces fluctuations in the melt pool depth, which increases the probability that, at low laser power, defects will form through a lack of powder fusion. Also, depending on their location relative to the scanning beam, spatter particles may be broken up, resulting in multiplication of the number of defect sites. In addition, spatter particles in motion may shadow the laser beam, interfering with deposition of laser energy and resulting in pore formation. With this detailed knowledge of the physics gained from simulations and synchrotron imaging, Khairallah et al. developed a macroscopic model to map out the expulsion regime as a function of laser power and laser scan speed. This “upscaling” of the physics for the full range of complex phenomena that occur during 3D printing of metals will ultimately build the confidence needed to use these technologies as reliable, full-production tools. Such understanding will also enable design of new alloys specifically tuned to the physics of the metal 3D printing process, expanding the presently very limited suite of printable metallic materials. 1. [↵][10]1. S. A. Khairallah et al ., Science 368, 660 (2020). [OpenUrl][11][Abstract/FREE Full Text][12] 2. [↵][13]1. R. R. Dehoff et al ., Mater. Sci. Technol. 31, 931 (2015). [OpenUrl][14] 3. [↵][15]1. W. E. King et al ., Appl. Phys. Rev. 2, 041304 (2015). [OpenUrl][16] 4. 1. D. D. Gu, 2. W. Meiners, 3. K. Wissenbach, 4. R. Poprawe , Int. Mater. Rev. 57, 133 (2012). [OpenUrl][17][CrossRef][18] 5. 1. T. DebRoy et al ., Prog. Mater. Sci. 92, 112 (2018). [OpenUrl][19][CrossRef][20] 6. [↵][21]1. S. S. Babu et al ., Metall. Mater. Trans. 49, 3764 (2018). [OpenUrl][22] 7. [↵][23]1. A. Klassen, 2. T. Scharowsky, 3. C. Korner , J. Phys. D Appl. Phys. 47, 275303 (2014). [OpenUrl][24] 8. [↵][25]1. C. A. Stewart, 2. S. P. Murray, 3. A. Suzuki, 4. T. M. Pollock, 5. C. G. Levi , Mater. Des. 189, 108445 (2020). [OpenUrl][26] 9. [↵][27]1. M. P. Echlin, 2. M. Straw, 3. S. Randolph, 4. J. Filevich, 5. T. M. Pollock , Mater. Charact. 100, 1 (2015). [OpenUrl][28] 10. [↵][29]1. C. L. A. Leung et al ., Mater. Des. 174, 107792 (2019). [OpenUrl][30] Acknowledgments: We acknowledge the support of Office of Naval Research (ONR) grant N00014-18-1-2794. [1]: #ref-1 [2]: #ref-2 [3]: #ref-3 [4]: #ref-6 [5]: #ref-7 [6]: #ref-8 [7]: #ref-9 [8]: #ref-10 [9]: pending:yes [10]: #xref-ref-1-1 "View reference 1 in text" [11]: {openurl}?query=rft.jtitle%253DScience%26rft.stitle%253DScience%26rft.aulast%253DKhairallah%26rft.auinit1%253DS.%2BA.%26rft.volume%253D368%26rft.issue%253D6491%26rft.spage%253D660%26rft.epage%253D665%26rft.atitle%253DControlling%2Binterdependent%2Bmeso-nanosecond%2Bdynamics%2Band%2Bdefect%2Bgeneration%2Bin%2Bmetal%2B3D%2Bprinting%26rft_id%253Dinfo%253Adoi%252F10.1126%252Fscience.aay7830%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [12]: /lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6Mzoic2NpIjtzOjU6InJlc2lkIjtzOjEyOiIzNjgvNjQ5MS82NjAiO3M6NDoiYXRvbSI7czoyMjoiL3NjaS8zNjgvNjQ5MS81ODMuYXRvbSI7fXM6ODoiZnJhZ21lbnQiO3M6MDoiIjt9 [13]: #xref-ref-2-1 "View reference 2 in text" [14]: {openurl}?query=rft.jtitle%253DMater.%2BSci.%2BTechnol.%26rft.volume%253D31%26rft.spage%253D931%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [15]: #xref-ref-3-1 "View reference 3 in text" [16]: {openurl}?query=rft.jtitle%253DAppl.%2BPhys.%2BRev.%26rft.volume%253D2%26rft.spage%253D041304%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [17]: {openurl}?query=rft.jtitle%253DInt.%2BMater.%2BRev.%26rft.volume%253D57%26rft.spage%253D133%26rft_id%253Dinfo%253Adoi%252F10.1179%252F1743280411Y.0000000014%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [18]: /lookup/external-ref?access_num=10.1179/1743280411Y.0000000014&link_type=DOI [19]: {openurl}?query=rft.jtitle%253DProg.%2BMater.%2BSci.%26rft.volume%253D92%26rft.spage%253D112%26rft_id%253Dinfo%253Adoi%252F10.1016%252Fj.pmatsci.2017.10.001%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [20]: /lookup/external-ref?access_num=10.1016/j.pmatsci.2017.10.001&link_type=DOI [21]: #xref-ref-6-1 "View reference 6 in text" [22]: {openurl}?query=rft.jtitle%253DMetall.%2BMater.%2BTrans.%26rft.volume%253D49%26rft.spage%253D3764%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [23]: #xref-ref-7-1 "View reference 7 in text" [24]: {openurl}?query=rft.jtitle%253DJ.%2BPhys.%2BD%2BAppl.%2BPhys.%26rft.volume%253D47%26rft.spage%253D275303%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [25]: #xref-ref-8-1 "View reference 8 in text" [26]: {openurl}?query=rft.jtitle%253DMater.%2BDes.%26rft.volume%253D189%26rft.spage%253D108445%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [27]: #xref-ref-9-1 "View reference 9 in text" [28]: {openurl}?query=rft.jtitle%253DMater.%2BCharact.%26rft.volume%253D100%26rft.spage%253D1%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [29]: #xref-ref-10-1 "View reference 10 in text" [30]: {openurl}?query=rft.jtitle%253DMater.%2BDes.%26rft.volume%253D174%26rft.spage%253D107792%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx
领域	气候变化 ; 资源环境
URL	查看原文
引用统计	被引频次：20[WOS] [WOS记录] [WOS相关记录]
文献类型	期刊论文
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/249786
专题	气候变化资源环境科学
推荐引用方式 GB/T 7714	Andrew T. Polonsky,Tresa M. Pollock. Closing the science gap in 3D metal printing[J]. Science,2020.
APA	Andrew T. Polonsky,&Tresa M. Pollock.(2020).Closing the science gap in 3D metal printing.Science.
MLA	Andrew T. Polonsky,et al."Closing the science gap in 3D metal printing".Science (2020).