Fabrication and Hardness Behaviour of High Entropy Alloys

  • Modupeola DadaEmail author
  • Patricia Popoola
  • Ntombi Mathe
  • Sisa Pityana
  • Samson Adeosun
  • Thabo Lengopeng
Conference paper
Part of the The Minerals, Metals & Materials Series book series (MMMS)


Laser additive manufacturing is a direct energy deposition process which manufactures components from 3D model data in progressive layers until a whole part is built as opposed subtractive manufacturing. However, during the procedure, the deposits are subjected to rapid thermal stresses which adversely impact the integrity of the built component. High entropy alloys are materials with complex compositions of multiple elements. Traditionally, these alloys are fabricated using casting and other machining processes, with a recent interest in the use of laser deposition as a possible manufacturing process. To optimize process parameters of high entropy alloys melted on a steel plate, the influence of preheating temperature on the overall quality, microstructure and hardness behaviour of the alloys for aerospace applications were investigated. In this research, 9 samples of AlCoCrFeNiCu and AlTiCrFeCoNi high entropy alloys were fabricated using different laser parameters. The phases, chemical composition, micro-hardness and structural morphologies were characterized with XRD, EDS, Vickers Microhardness tester and SEM respectively before and after preheating the base plates at 400 °C. Experimental results show extensive cracking on all the samples without preheating while after preheating all samples were observed to be crack-free. Although, there were no variations on the dendritic structures in the optical micrographs with and without preheating temperature, there were notable changes in the phases and hardness behaviour of the alloys showing that preheating the base plate from 400 °C significantly influences the mechanical properties of additive manufactured high entropy alloys and contributes to the elimination of cracks induced by thermal stresses.


Base plate preheating High entropy alloys Laser additive manufacturing Optimal parameters Thermal stresses 


  1. 1.
    Owen DG (2001) Manufacturing Defects. SCL Rev 53:851Google Scholar
  2. 2.
    Oberländer B, Lugscheider E (1992) Comparison of properties of coatings produced by laser cladding and conventional methods. Mater Sci Technol 8(8):657–665CrossRefGoogle Scholar
  3. 3.
    Lepski D, Brückner F (2009) Laser cladding. In: The theory of laser materials processing. Springer, Berlin, pp 235–279Google Scholar
  4. 4.
    Brückner F, Lepski D (2017) Laser cladding. In: The theory of laser materials processing. Springer, Berlin, pp 263–306Google Scholar
  5. 5.
    Nazemi N, Urbanic J, Alam M (2017) Hardness and residual stress modeling of powder injection laser cladding of P420 coating on AISI 1018 substrate. Int J Adv Manuf Technol 93(9–12):3485–3503CrossRefGoogle Scholar
  6. 6.
    Brückner F, Lepski D, Beyer E (2007) Modeling the influence of process parameters and additional heat sources on residual stresses in laser cladding. J Therm Spray Technol 16(3):355–373CrossRefGoogle Scholar
  7. 7.
    Eslami MR et al (2013) Theory of elasticity and thermal stresses, vol 197. Springer, BerlinGoogle Scholar
  8. 8.
    Clyne T, Gill S (1996) Residual stresses in thermal spray coatings and their effect on interfacial adhesion: a review of recent work. J Therm Spray Technol 5(4):401CrossRefGoogle Scholar
  9. 9.
    Zumofen L et al (2017) Quality related effects of the preheating temperature on laser melted high carbon content steels. In: International conference on additive manufacturing in products and applications. Springer, BerlinGoogle Scholar
  10. 10.
    Malý M et al (2019) Effect of process parameters and high-temperature preheating on residual stress and relative density of Ti6Al4V processed by selective laser melting. Materials 12(6):930CrossRefGoogle Scholar
  11. 11.
    Casati R et al (2018) Effects of platform pre-heating and thermal-treatment strategies on properties of AlSi10Mg alloy processed by selective laser melting. Metals 8(11):954CrossRefGoogle Scholar
  12. 12.
    Danlos Y et al (2008) Combining effects of ablation laser and laser preheating on metallic substrates before thermal spraying. Surf Coat Technol 202(18):4531–4537CrossRefGoogle Scholar
  13. 13.
    Aghasibeig M, Fredriksson H (2012) Laser cladding of a featureless iron-based alloy. Surf Coat Technol 209:32–37CrossRefGoogle Scholar
  14. 14.
    Zhang H et al (2010) Laser cladding of Colmonoy 6 powder on AISI316L austenitic stainless steel. Nucl Eng Des 240(10):2691–2696CrossRefGoogle Scholar
  15. 15.
    Khaled T (2014) Preheating, interpass and post-weld heat treatment requirements for welding low alloy steels, vol 6, pp 1–14Google Scholar
  16. 16.
    Pradhan A et al (2014) Extreme tunability in aluminum doped zinc oxide plasmonic materials for near-infrared applications. Scientific reports, vol 4, p 6415Google Scholar
  17. 17.
    Wang W-R et al (2012) Effects of Al addition on the microstructure and mechanical property of AlxCoCrFeNi high-entropy alloys. Intermetallics 26:44–51CrossRefGoogle Scholar
  18. 18.
    Dieter G (1988) Mechanical metallurgy, 3rd edn. McGraw-Hill, LondonGoogle Scholar
  19. 19.
    Wang W et al (2016) Liquid phase separation and rapid dendritic growth of high-entropy CoCrCuFeNi alloy. Intermetallics 77:41–45CrossRefGoogle Scholar
  20. 20.
    Tong C-J et al (2005) Microstructure characterization of Al x CoCrCuFeNi high-entropy alloy system with multiprincipal elements. Metall Mater Trans A 36(4):881–893CrossRefGoogle Scholar
  21. 21.
    Qiu X-W (2013) Microstructure and properties of AlCrFeNiCoCu high entropy alloy prepared by powder metallurgy. J Alloy Compd 555:246–249CrossRefGoogle Scholar
  22. 22.
    Ding C et al (2018) Effects of substrate preheating temperatures on the microstructure, properties, and residual stress of 12CrNi2 prepared by laser cladding deposition technique. Materials 11(12):2401CrossRefGoogle Scholar

Copyright information

© The Minerals, Metals & Materials Society 2020

Authors and Affiliations

  • Modupeola Dada
    • 1
    Email author
  • Patricia Popoola
    • 1
  • Ntombi Mathe
    • 2
  • Sisa Pityana
    • 2
  • Samson Adeosun
    • 3
  • Thabo Lengopeng
    • 2
  1. 1.Chemical, Metallurgical and Materials EngineeringTshwane University of TechnologyPretoriaSouth Africa
  2. 2.Council for Scientific and Industrial ResearchPretoriaSouth Africa
  3. 3.Metallurgical and Materials EngineeringUniversity of LagosAkokaNigeria

Personalised recommendations