Thermal Decomposition of Massive Phase to Fine Lamellar α/β in Ti–6Al–4V Additively Manufactured Alloy by Directed Energy Deposition
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The occurrence of a massive phase (αm) transformation and a thermal decomposition of an αm to fine lamellar α/β with an α lamellar width of approximately 1 µm have been identified in additively manufactured Ti–6Al–4V alloy by directed energy deposition. The β to αm phase transformation during additive manufacturing generated a high dislocation density, which was calculated by the kernel average misorientation. This caused a significant change in the Gibbs free energy of α, resulting in the nucleation of the β phase becoming preferable in the area with high dislocation density at temperature below the β-transus temperature. Subsequent annealing at 850 °C altered the massive morphology to lamellar due to the formation of a β phase between α lamellar boundaries.
KeywordsMassive phase transformation Titanium alloys Dislocation Misorientation Phase stability Additive manufacturing
This work was supported by the Korea Evaluation Institute of Industrial Technology (KEIT) Granted financial resource from Ministry of Trade, Industry, and Energy, Republic of Korea (No. 10062485) and IONS Co. Ltd.
- 8.R.W. Cahn, P. Haasen, Physical Metallurgy, 4th edn. (North Holland, Amsterdam, 1996)Google Scholar
- 18.O.M. Ivasishin, D.G. Savvakin, The impact of diffusion on synthesis of high-strength titanium alloys from elemental powder blends. Key Eng. Mater. 436, 113–121 (2010). https://doi.org/10.4028/www.scientific.net/KEM.436.113 CrossRefGoogle Scholar
- 19.M.J. Donachie, Jr., Titanium: A Technical Guide, 2nd ed. (ASM Int., Ohio, 2000)Google Scholar
- 26.J.D. Beal, R. Boyer, D. Sanders, T.B. Company, forming of titanium and titanium alloys, in: ASM Handbook 14B, Metalworking: Sheet Forming, ed. S.L. Semiatin (ASM Int., Russell Township, 2006), pp. 656–669Google Scholar
- 27.G.E. Dieter, D. Bacon, Mechanical Metallurgy: SI Metric Edition (McGraw-Hill Book Company, London, 1988)Google Scholar
- 28.K. Mutombo, C. Siyasiya, W.E. Stumpf, Dynamic globularization of α-phase in Ti6Al4V alloy during hot compression. Mater. Sci. Forum 783–786, 584–590 (2014). https://doi.org/10.4028/www.scientific.net/MSF.783-786.584 CrossRefGoogle Scholar
- 31.R. Boyer, G. Welsch, E.W. Collings, ASM Materials Properties Handbook: Titanium Alloys (ASM Int., Russell Township, 1994)Google Scholar