Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Additive manufacturing of ultrafine-grained high-strength titanium alloys

An Author Correction to this article was published on 28 May 2020

This article has been updated


Additive manufacturing, often known as three-dimensional (3D) printing, is a process in which a part is built layer-by-layer and is a promising approach for creating components close to their final (net) shape. This process is challenging the dominance of conventional manufacturing processes for products with high complexity and low material waste1. Titanium alloys made by additive manufacturing have been used in applications in various industries. However, the intrinsic high cooling rates and high thermal gradient of the fusion-based metal additive manufacturing process often leads to a very fine microstructure and a tendency towards almost exclusively columnar grains, particularly in titanium-based alloys1. (Columnar grains in additively manufactured titanium components can result in anisotropic mechanical properties and are therefore undesirable2.) Attempts to optimize the processing parameters of additive manufacturing have shown that it is difficult to alter the conditions to promote equiaxed growth of titanium grains3. In contrast with other common engineering alloys such as aluminium, there is no commercial grain refiner for titanium that is able to effectively refine the microstructure. To address this challenge, here we report on the development of titanium–copper alloys that have a high constitutional supercooling capacity as a result of partitioning of the alloying element during solidification, which can override the negative effect of a high thermal gradient in the laser-melted region during additive manufacturing. Without any special process control or additional treatment, our as-printed titanium–copper alloy specimens have a fully equiaxed fine-grained microstructure. They also display promising mechanical properties, such as high yield strength and uniform elongation, compared to conventional alloys under similar processing conditions, owing to the formation of an ultrafine eutectoid microstructure that appears as a result of exploiting the high cooling rates and multiple thermal cycles of the manufacturing process. We anticipate that this approach will be applicable to other eutectoid-forming alloy systems, and that it will have applications in the aerospace and biomedical industries.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Fig. 1: Additive manufacturing of Ti–6Al–4V and Ti–8.5Cu alloys.
Fig. 2: Scanning electron microscopy (SEM) characterization of Ti–8.5Cu alloy.
Fig. 3: Transmission electron microscopy characterization of as-printed Ti–8.5Cu alloy.
Fig. 4: Mechanical properties of as-printed Ti–Cu alloys.

Data availability

The datasets generated or analysed during the current study are available from the corresponding author on reasonable request.

Change history

  • 28 May 2020

    An amendment to this paper has been published and can be accessed via a link at the top of the paper.


  1. 1.

    Zhang, D. et al. Metal alloys for fusion-based additive manufacturing. Adv. Eng. Mater. 20, 1700952 (2018).

    Article  Google Scholar 

  2. 2.

    Carroll, B. E., Palmer, T. A. & Beese, A. M. Anisotropic tensile behavior of Ti–6Al–4V components fabricated with directed energy deposition additive manufacturing. Acta Mater. 87, 309–320 (2015).

    CAS  Article  Google Scholar 

  3. 3.

    Herzog, D., Seyda, V., Wycisk, E. & Emmelmann, C. Additive manufacturing of metals. Acta Mater. 117, 371–392 (2016).

    CAS  Article  Google Scholar 

  4. 4.

    StJohn, D. H., Qian, M., Easton, M. A. & Cao, P. The Interdependence Theory: the relationship between grain formation and nucleant selection. Acta Mater. 59, 4907–4921 (2011).

    CAS  Article  Google Scholar 

  5. 5.

    StJohn, D. H. et al. The challenges associated with the formation of equiaxed grains during additive manufacturing of titanium alloys. Key Eng. Mater. 770, 155–164 (2018).

    Article  Google Scholar 

  6. 6.

    Bermingham, M. J., McDonald, S. D., StJohn, D. H. & Dargusch, M. S. Beryllium as a grain refiner in titanium alloys. J. Alloys Compd. 481, L20–L23 (2009).

    CAS  Article  Google Scholar 

  7. 7.

    Cardoso, F. F. et al. Hexagonal martensite decomposition and phase precipitation in Ti–Cu alloys. Mater. Des. 32, 4608–4613 (2011).

    CAS  Article  Google Scholar 

  8. 8.

    Xu, W., Lui, E. W., Pateras, A., Qian, M. & Brandt, M. In situ tailoring microstructure in additively manufactured Ti–6Al–4V for superior mechanical performance. Acta Mater. 125, 390–400 (2017).

    CAS  Article  Google Scholar 

  9. 9.

    Mitzner, S., Liu, S., Domack, M. S. & Hafley, R. A. Grain refinement of freeform fabricated Ti6Al4V alloy using beam/arc modulation. In 23rd Solid Freeform Fabrication Symp. 536–555 (2012);

  10. 10.

    Wang, F., Williams, S. & Rush, M. Morphology investigation on direct current pulsed gas tungsten arc welded additive layer manufactured Ti6Al4V alloy. Int. J. Adv. Manuf. Technol. 57, 597–603 (2011).

    Article  Google Scholar 

  11. 11.

    Mereddy, S. et al. Trace carbon addition to refine microstructure and enhance properties of additive-manufactured Ti–6Al–4V. JOM 70, 1670–1676 (2018).

    CAS  Article  Google Scholar 

  12. 12.

    Wang, J. et al. Grain morphology evolution and texture characterization of wire and arc additive manufactured Ti–6Al–4V. J. Alloys Compd. 768, 97–113 (2018).

    CAS  Article  Google Scholar 

  13. 13.

    Li, Z., Li, J., Zhu, Y., Tian, X. & Wang, H. Variant selection in laser melting deposited α + β titanium alloy. J. Alloys Compd. 661, 126–135 (2016).

    CAS  Article  Google Scholar 

  14. 14.

    Zhu, Y.-Y., Tang, H.-B., Li, Z., Xu, C. & He, B. Solidification behavior and grain morphology of laser additive manufacturing titanium alloys. J. Alloys Compd. 777, 712–716 (2019).

    CAS  Article  Google Scholar 

  15. 15.

    Zhu, Y., Liu, D., Tian, X., Tang, H. & Wang, H. Characterization of microstructure and mechanical properties of laser melting deposited Ti–6.5Al–3.5Mo–1.5Zr–0.3Si titanium alloy. Mater. Des. 56, 445–453 (2014).

    CAS  Article  Google Scholar 

  16. 16.

    Kurz, W. & Fisher, D. J. Fundamentals of Solidification 3rd edn (Trans Tech Publications, 1989).

  17. 17.

    Fulcher, B. A., Leigh, D. K. & Watt, T. J. Comparison of AlSi10Mg and Al 6061 processed through DMLS. In Proc. Solid Freeform Fabrication (SFF) Symp. 46, 404–419 (2014).

  18. 18.

    Easton, M., Wang, H., Grandfield, J., StJohn, D. & Sweet, E. An analysis of the effect of grain refinement on the hot tearing of aluminium alloys. Mater. Forum 28, 224–229 (2004).

    CAS  Google Scholar 

  19. 19.

    Souza, S. A., Afonso, C. R. M., Ferrandini, P. L., Coelho, A. A. & Caram, R. Effect of cooling rate on Ti–Cu eutectoid alloy microstructure. Mater. Sci. Eng. C 29, 1023–1028 (2009).

    CAS  Article  Google Scholar 

  20. 20.

    Williams, J. C., Taggart, R. & Polonis, D. H. The morphology and substructure of Ti–Cu martensite. Metall. Trans. 1, 2265–2270 (1970).

    CAS  Article  Google Scholar 

  21. 21.

    Brandes, E. A. & Brook, G. B. Smithells Metals Reference Book 7th edn (Butterworth-Heinemann, 1992).

  22. 22.

    Zhang, E., Wang, X., Chen, M. & Hou, B. Effect of the existing form of Cu element on the mechanical properties, bio-corrosion and antibacterial properties of Ti–Cu alloys for biomedical application. Mater. Sci. Eng. C 69, 1210–1221 (2016).

    CAS  Article  Google Scholar 

  23. 23.

    Ren, Y. M. et al. Microstructure and deformation behavior of Ti–6Al–4V alloy by high-power laser solid forming. Acta Mater. 132, 82–95 (2017).

    CAS  Article  Google Scholar 

  24. 24.

    Kok, Y. et al. Anisotropy and heterogeneity of microstructure and mechanical properties in metal additive manufacturing: a critical review. Mater. Des. 139, 565–586 (2018).

    CAS  Article  Google Scholar 

  25. 25.

    Hayama, A. O. F. et al. Effects of composition and heat treatment on the mechanical behavior of Ti–Cu alloys. Mater. Des. 55, 1006–1013 (2014).

    CAS  Article  Google Scholar 

  26. 26.

    Kikuchi, M. et al. Mechanical properties and microstructures of cast Ti–Cu alloys. Dent. Mater. 19, 174–181 (2003).

    CAS  Article  Google Scholar 

  27. 27.

    Liu, R. et al. Antibacterial effect of copper-bearing titanium alloy (Ti–Cu) against Streptococcus mutans and Porphyromonas gingivalis. Sci. Rep. 6, 29985 (2016).

    ADS  CAS  Article  Google Scholar 

  28. 28.

    Easton, M. A., Qian, M., Prasad, A. & StJohn, D. H. Recent advances in grain refinement of light metals and alloys. Curr. Opin. Solid State Mater. Sci. 20, 13–24 (2016).

    ADS  CAS  Article  Google Scholar 

  29. 29.

    Schmid-Fetzer, R. & Kozlov, A. Thermodynamic aspects of grain growth restriction in multicomponent alloy solidification. Acta Mater. 59, 6133–6144 (2011).

    CAS  Article  Google Scholar 

  30. 30.

    Okamoto, H. Phase Diagrams For Binary Alloys 2nd edn (ASM International, 2010).

Download references


We acknowledge the Australian Research Council (ARC) for financial support (grant number DP160100560). D.Q. would like to thank the RMIT Vice-Chancellor’s Senior Research Fellowship Fund for support. We thank M. Brandt and A. Jones for their support during laser metal deposition manufacturing, K. Yang for her support in etching additively manufactured titanium samples and E. Lui for his support in tensile testing. We acknowledge the facilities, and the scientific and technical assistance, of the RMIT Microscopy and Microanalysis Facility (RMMF). We also acknowledge the Center for Electron Microscopy and Analysis (CEMAS) at the Ohio State University for providing access to research facilities.

Author information




M.A.E., M.A.G., D.H.StJ. and H.L.F. conceived the idea. D.Q. and D.Z. designed the experiments. D.Z. and D.Q. helped with processing parameter development and sample manufacturing, and performed the microstructure characterization. Y.Z. and D.Z. conducted the transmission electron microscopy and analysed the results. D.Z. performed mechanical testing, simulations and X-ray computed tomography. M.A.E. supervised the project. D.Z. and D.Q. drafted the manuscript. All authors discussed the results and edited the manuscript at all stages.

Corresponding authors

Correspondence to Hamish L. Fraser or Mark A. Easton.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Peer review information Nature thanks Amy Clarke, David Dye and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Extended data figures and tables

Extended Data Fig. 1 Ti–Cu phase diagram.

Portion of the Ti–Cu phase diagram indicating the compositions selected for laser metal deposition. We selected 3.5, 6.5 and 8.5 wt% copper to explore the behaviour of hypo-eutectoid, eutectoid and hyper-eutectoid compositions under additive manufacturing. This figure is adapted from ref. 30, with the permission of ASM International.

Extended Data Fig. 2 3D visualization of the porosity of the manufactured specimens in the xyz coordinate system.

a, Ti–3.5Cu. b, Ti–6.5Cu. c, Ti–8.5Cu. d, Calculated relative density of the as-printed specimens. Error bars represent one standard deviation.

Extended Data Fig. 3 XEDS results of the copper content along the building direction for Ti–8.5Cu alloy.

The base point is 0 mm and the chemical composition is homogeneous. Error bars represent one standard deviation.

Extended Data Fig. 4 Polarized optical microstructures.

a, b, The equiaxed grains of as-printed Ti–3.5Cu (a) and Ti–6.5Cu (b). The average grain size is 69.8 μm for Ti–3.5Cu and 16.3 μm for Ti–6.5Cu.

Extended Data Fig. 5 Solidification curves.

The data are shown for different copper compositions under equilibrium and Scheil conditions. The Scheil curves show a substantially enlarged temperature interval between liquidus and solidus temperatures compared with the equilibrium condition.

Extended Data Fig. 6 XRD spectra.

Experimental XRD spectra collected from the as-printed Ti–8.5Cu alloy indicates that only two phases are present in the specimen: α-phase titanium and Ti2Cu.

Extended Data Fig. 7 BSE images.

ad, BSE images of as-printed specimens showing the fine α phases when multiple layers were deposited, for Ti–3.5Cu (a) and Ti–6.5Cu (b); and the martensite phase when only a single layer was deposited for Ti–3.5Cu (c) and Ti–6.5Cu (d). Images were taken at the first layer of build specimens, indicated by the red spots.

Extended Data Fig. 8 SEM images of the cross-section of raw powders.

a, b, SEM images of the titanium powder (a) and copper powder (b) cross-sections. The powders are spherical in shape with a diameter between 50 µm and 100 µm, and porosity can be observed within some powder particles. The yellow arrows indicate examples where powder particles fell out of the resin during the polishing process.

Extended Data Fig. 9 Engineering stress–strain curves.

The data for the additively manufactured materials tested in this study indicate good repeatability.

Extended Data Table 1 Measured chemical compositions (wt%) and volume fraction of eutectoid lamellae in the as-printed alloys

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Zhang, D., Qiu, D., Gibson, M.A. et al. Additive manufacturing of ultrafine-grained high-strength titanium alloys. Nature 576, 91–95 (2019).

Download citation

Further reading


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing