Effects of Cu addition and heat treatment on the microstructure and hardness of pure Ti prepared by Selective laser melting (SLM)

Document Type : Research Paper

Authors

1 Department of Materials Engineering, Imam Khomeini International University (IKIU), Qazvin, 3414896818, Iran.

2 Department of Materials Engineering, Imam Khomeini International University (IKIU), Qazvin, 3414896818, Iran;

3 Department of Management and Production Engineering, Politecnico di Torino, Torino, 10129, Italy.

4 Department of Materials Engineering, Isfahan University of Technology (IUT), Isfahan, 8415683111, Iran.

Abstract

Formation of strong texture, columnar grains, and chemical inhomogeneity are some of the serious challenges associated with SLM of metallic alloys. This paper deals with in-situ SLM manufacturing of Ti-5Cu (wt.%) samples from pure Ti and Cu powders at a constant volumetric energy density (VED) of 50.26 J/mm3. The heat treatment of samples was carried out by heating at 1050 °C (above the β-transus temperature) for 3hr followed by furnace cooling. Then the effects of Cu addition to pure Ti and heat treatment on β-columnar to equiaxed transition (CET) morphology and size of the α phase as well as microhardness of pure Ti and Ti-5Cu samples were investigated. The results showed that the β columnar grains with an average equivalent diameter (deq) of 80 μm in SLMed pure Ti were effectively converted to equiaxed grains with an average deq of ~15 μm in the SLMed Ti-5Cu samples. The Cu addition increased the average microhardness from ~290 HV for pure Ti to ~415 HV for Ti-5Cu samples. This was attributed to the formation of equiaxed grains, increased lattice micro-strain resulting from Cu addition and decreased size of the lath-like α phase. The applied heat treatment led to the formation of equiaxed β grains with an average diameter of ~125 μm, dissolution of unmelted titanium particles and the non-dissolution zones of Cu and Ti, and a rather homogeneous structure in Ti-5Cu samples. It also resulted in the decomposition of α´ martensitic structure and the formation of different morphologies of Ti2Cu precipitates. Reduction of the average microhardness of the Ti-5Cu samples to ~312 HV after heat treatment was also related to the increase in deq of the equiaxed β grains, in addition to the increase in the size of the α laths phase and decrease in micro-strain.

Keywords


  1. Zhang D, Sun S, Qiu D, Gibson MA, Dargusch MS, Brandt M, et al. Metal Alloys for Fusion‐Based Additive Manufacturing. Advanced Engineering Materials. 2018;20(5).
  2. Collins PC, Brice DA, Samimi P, Ghamarian I, Fraser HL. Microstructural Control of Additively Manufactured Metallic Materials. Annual Review of Materials Research. 2016;46(1):63-91.
  3. Mosallanejad MH, Niroumand B, Ghibaudo C, Biamino S, Salmi A, Fino P, Saboori A. In-situ alloying of a fine grained fully equiaxed Ti-based alloy via electron beam powder bed fusion additive manufacturing process. Additive Manufacturing. 2022;56:102878.
  4. Leung CLA, Tosi R, Muzangaza E, Nonni S, Withers PJ, Lee PD. Effect of preheating on the thermal, microstructural and mechanical properties of selective electron beam melted Ti-6Al-4V components. Materials & Design. 2019;174:107792.
  5. Carroll BE, Palmer TA, Beese AM. Anisotropic tensile behavior of Ti–6Al–4V components fabricated with directed energy deposition additive manufacturing. Acta Materialia. 2015;87:309-20.
  6. M. J. Bermingham, D. H, StJohn, b. J. Krynen, S. Tedman-Jones, M. S. Dargusch, Promoting the columnar to equiaxed transition and grain refinement of titanium alloys during additive manufacturing, Acta Mater., 168, 2019, 261–274.
  7. Fan Z, Gao F, Zhou L, Lu SZ. A new concept for growth restriction during solidification. Acta Materialia. 2018;152:248-57.
  8. Bermingham M, StJohn D, Easton M, Yuan L, Dargusch M. Revealing the Mechanisms of Grain Nucleation and Formation During Additive Manufacturing. JOM. 2020;72(3):1065-73.
  9. Vilardell AM, Takezawa A, du Plessis A, Takata N, Krakhmalev P, Kobashi M, et al. Mechanical behavior of in-situ alloyed Ti6Al4V(ELI)-3 at.% Cu lattice structures manufactured by laser powder bed fusion and designed for implant applications. Journal of the Mechanical Behavior of Biomedical Materials. 2021;113:104130.
  10. Del Guercio G, Galati M, Saboori A, Fino P, Iuliano L. Microstructure and Mechanical Performance of Ti–6Al–4V Lattice Structures Manufactured via Electron Beam Melting (EBM): A Review. Acta Metallurgica Sinica (English Letters). 2020;33(2):183-203.
  11. Abdel-Hady Gepreel M, Niinomi M. Biocompatibility of Ti-alloys for long-term implantation. Journal of the Mechanical Behavior of Biomedical Materials. 2013;20:407-15.
  12. Xu X, Lu Y, Li S, Guo S, He M, Luo K, Lin J. Copper-modified Ti6Al4V alloy fabricated by selective laser melting with pro-angiogenic and anti-inflammatory properties for potential guided bone regeneration applications. Materials Science and Engineering: C. 2018;90:198-210.
  13. Zhang D, Qiu D, Gibson MA, Zheng Y, Fraser HL, StJohn DH, Easton MA. Additive manufacturing of ultrafine-grained high-strength titanium alloys. Nature. 2019;576(7785):91-5.
  14. Zhang F, Mei M, Al-Hamdani K, Tan H, Clare AT. Novel nucleation mechanisms through satelliting in direct metal deposition of Ti-15Mo. Materials Letters. 2018;213:197-200.
  15. Mantri SA, Alam T, Choudhuri D, Yannetta CJ, Mikler CV, Collins PC, Banerjee R. The effect of boron on the grain size and texture in additively manufactured β-Ti alloys. Journal of Materials Science. 2017;52(20):12455-66.
  16. Mereddy S, Bermingham MJ, StJohn DH, Dargusch MS. Grain refinement of wire arc additively manufactured titanium by the addition of silicon. Journal of Alloys and Compounds. 2017;695:2097-103.
  17. Mendoza MY, Samimi P, Brice DA, Martin BW, Rolchigo MR, LeSar R, Collins PC. Microstructures and Grain Refinement of Additive-Manufactured Ti-xW Alloys. Metallurgical and Materials Transactions A. 2017;48(7):3594-605.
  18. Krakhmalev P, Yadroitsev I, Yadroitsava I, de Smidt O. Functionalization of Biomedical Ti6Al4V via In Situ Alloying by Cu during Laser Powder Bed Fusion Manufacturing. Materials (Basel). 2017;10(10):1154.
  19. Mosallanejad MH, Niroumand B, Aversa A, Saboori A. In-situ alloying in laser-based additive manufacturing processes: A critical review. Journal of Alloys and Compounds. 2021;872:159567.
  20. Mosallanejad MH, Niroumand B, Ghibaudo C, Biamino S, Salmi A, Fino P, Saboori A. In-situ alloying of a fine grained fully equiaxed Ti-based alloy via electron beam powder bed fusion additive manufacturing process. Additive Manufacturing. 2022;56:102878.

21 Su C, Yu H, Wang Z, Yang J, Zeng X. Controlling the tensile and fatigue properties of selective laser melted Ti–6Al–4V alloy by post treatment. Journal of Alloys and Compounds. 2021;857:157552.

22 Galarraga H, Warren RJ, Lados DA, Dehoff RR, Kirka MM, Nandwana P. Effects of heat treatments on microstructure and properties of Ti-6Al-4V ELI alloy fabricated by electron beam melting (EBM). Materials Science and Engineering: A. 2017;685:417-28.

  1. Martín Vilardell A, Cantillo Alzamora V, Bauso LV, Madrid C, Krakhmalev P, Albu M, et al. Effect of Heat Treatment on Osteoblast Performance and Bactericidal Behavior of Ti6Al4V(ELI)-3at.%Cu Fabricated by Laser Powder Bed Fusion. J Funct Biomater. 2023;14(2):63.
  2. Qin P, Liu Y, Sercombe TB, Li Y, Zhang C, Cao C, et al. Improved Corrosion Resistance on Selective Laser Melting Produced Ti-5Cu Alloy after Heat Treatment. ACS Biomaterials Science & Engineering. 2018;4(7):2633-42.
  3. Schmid-Fetzer R, Kozlov A. Thermodynamic aspects of grain growth restriction in multicomponent alloy solidification. Acta Materialia. 2011;59(15):6133-44.
  4. Liu S, Shin YC. Additive manufacturing of Ti6Al4V alloy: A review. Materials & Design. 2019;164:107552.
  5. Wysocki B, Maj P, Krawczyńska A, Rożniatowski K, Zdunek J, Kurzydłowski KJ, Święszkowski W. Microstructure and mechanical properties investigation of CP titanium processed by selective laser melting (SLM). Journal of Materials Processing Technology. 2017;241:13-23.
  6. Li XP, Van Humbeeck J, Kruth JP. Selective laser melting of weak-textured commercially pure titanium with high strength and ductility: A study from laser power perspective. Materials & Design. 2017;116:352-8.
  7. Zhang B, Liao H, Coddet C. Microstructure evolution and density behavior of CP Ti parts elaborated by Self-developed vacuum selective laser melting system. Applied Surface Science. 2013;279:310-6.
  8. StJohn DH, Qian M, Easton MA, Cao P. The Interdependence Theory: The relationship between grain formation and nucleant selection. Acta Materialia. 2011;59(12):4907-21.
  9. Mantri SA, Alam T, Choudhuri D, Yannetta CJ, Mikler CV, Collins PC, Banerjee R. The effect of boron on the grain size and texture in additively manufactured β-Ti alloys. Journal of Materials Science. 2017;52(20):12455-66.
  10. Xue A, Wang L, Lin X, Wang J, Chen J, Huang W. Effect of boron on the microstructure and mechanical properties of Ti-6Al-4V produced by laser directed energy deposition after heat treatment. Journal of Laser Applications. 2020;32(1).
  11. Xue A, Lin X, Wang L, Wang J, Huang W. Influence of trace boron addition on microstructure, tensile properties and their anisotropy of Ti6Al4V fabricated by laser directed energy deposition. Materials & Design. 2019;181:107943.
  12. Zhang K, Tian X, Bermingham M, Rao J, Jia Q, Zhu Y, et al. Effects of boron addition on microstructures and mechanical properties of Ti-6Al-4V manufactured by direct laser deposition. Materials & Design. 2019;184:108191.
  13. Yadroitsev I, Krakhmalev P, Yadroitsava I. Titanium Alloys Manufactured by In Situ Alloying During Laser Powder Bed Fusion. JOM. 2017;69(12):2725-30.
  14. Vrancken B, Thijs L, Kruth J-P, Van Humbeeck J. Heat treatment of Ti6Al4V produced by Selective Laser Melting: Microstructure and mechanical properties. Journal of Alloys and Compounds. 2012;541:177-85.
  15. Raghavan S, Nai MLS, Wang P, Sin WJ, Li T, Wei J. Heat treatment of electron beam melted (EBM) Ti-6Al-4V: microstructure to mechanical property correlations. Rapid Prototyping Journal. 2018;24(4):774-83.
  16. Donachie MJ. Titanium: a technical guide. ASM international; 2000.
  17. Zhao D, Chen Y, Jiang C, Li Y, Zhao Q, Xu Y, et al. Morphological evolution of Ti2Cu in Ti-13Cu-Al alloy after cooling from semi-solid state. Journal of Alloys and Compounds. 2020;848:156639.
  18. Yadav P, Saxena KK. Effect of heat-treatment on microstructure and mechanical properties of Ti alloys: An overview. Materials Today: Proceedings. 2020;26:2546-57.
  19. Hemmasian Ettefagh A, Zeng C, Guo S, Raush J. Corrosion behavior of additively manufactured Ti-6Al-4V parts and the effect of post annealing. Additive Manufacturing. 2019;28:252-8.
  20. Li L, Chen Y, Lu Y, Qin S, Huang G, Huang T, Lin J. Effect of heat treatment on the corrosion resistance of selective laser melted Ti6Al4V3Cu alloy. Journal of Materials Research and Technology. 2021;12:904-15.
  21. Oh JM, Lim JW, Lee BG, Suh CY, Cho SW, Lee SW, Choi GS. Grain Refinement and Hardness Increase of Titanium via Trace Element Addition. MATERIALS TRANSACTIONS. 2010;51(11):2009-12.