Metals and Materials International

, Volume 25, Issue 6, pp 1428–1435 | Cite as

Thermal Decomposition of Massive Phase to Fine Lamellar α/β in Ti–6Al–4V Additively Manufactured Alloy by Directed Energy Deposition

  • Ghozali Suprobo
  • Abdul Azis Ammar
  • Nokeun ParkEmail author
  • Eung Ryul BaekEmail author
  • Sungwook Kim


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.

Graphical Abstract


Massive 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.


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Copyright information

© The Korean Institute of Metals and Materials 2019

Authors and Affiliations

  1. 1.School of Materials Science and EngineeringYeungnam UniversityGyeongsanRepublic of Korea
  2. 2.Industrial Materials Research GroupResearch Institute of Industrial Science and TechnologyPohangRepublic of Korea
  3. 3.Institute of Materials TechnologyYeungnam UniversityGyeongsan-siSouth Korea

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