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Effect of cobalt addition on microstructure and mechanical properties of tungsten heavy alloys

  • U. Ravi Kiran
  • M. Sankaranarayana
  • G. V. S. Nageswara Rao
  • T. K. Nandy
Technical Paper

Abstract

The present investigation attempts to study the microstructure and mechanical behaviour of tungsten heavy alloys with different cobalt content. Alloys with 2 and 3% cobalt were synthesized using liquid phase sintering technique. The alloys were then vacuum heat treated and finally swaged. Quantitative microstructural analyses were undertaken by determining tungsten grain size, contiguity of tungsten and volume fraction of the matrix etc. Tensile results showed that the alloy with 3% cobalt exhibited inferior properties as compared to 2% cobalt alloy. Detailed microstructural and fractographic analysis were undertaken in order to understand these trends. Work hardening analysis showed the double slope behaviour of the alloys, which could be attributed to change in deformation behaviour from single phase matrix to two phase aggregate. It was also concluded that higher cobalt alloys needed further optimization in terms of thermo-mechanical treatment in order to realize their full potential in terms of mechanical properties.

Keywords

Tungsten heavy alloy Microstructure Mechanical properties Fractograph 

Notes

Acknowledgements

The work was supported by the finance provided by DRDO. The authors convey their sincere gratitude to Dr. S. V. Kamat, Distinguished Scientist and Director, DMRL for encouragement and kind permission to publish this work.

References

  1. 1.
    Lenel F V, and Metal F V, Powder Metallurgy: Principles and Applications, Metal Powder Industries Federation, Princeton (1980).Google Scholar
  2. 2.
    Ariel E, Barta J, and Brandon P, Powder Metall Int 5 (1973)126.Google Scholar
  3. 3.
    German R M, Bourguignon L L, and Rabin B H, J Met 37 (1985) 36.Google Scholar
  4. 4.
    German R M, and Churn K S, Metall Trans A 15A (1984) 747.CrossRefGoogle Scholar
  5. 5.
    Noh JW, Kim E P, Song H S, Baek W H, Churn K S, and Kang S J L, Metall Trans 24 (1993) 2411.CrossRefGoogle Scholar
  6. 6.
    Kim E P, Hong M H, Baek W H, and Moon I H, Metall Mater Trans 30 (1999) 627.CrossRefGoogle Scholar
  7. 7.
    Xiang D P, Ding L, Chen X Y, and Zhang T M, Mater Sci Eng A 578 (2013) 18.CrossRefGoogle Scholar
  8. 8.
    Bose A, Jerman G, and German R M, Powder Metall Int 3 (1989) 9.Google Scholar
  9. 9.
    Bose A, German R M, and Gustafson D A, N J 19 (1988) 139.Google Scholar
  10. 10.
    Bose A, Sims D, and German R M, Prog Powder Metall 43 (1987) 79.Google Scholar
  11. 11.
    Bose A, and German R M, Metall Trans 19A (1988) 3100.CrossRefGoogle Scholar
  12. 12.
    Long T X, Fu L D, Trans Nonferrous Metals Soc China 5 (2004) 14.Google Scholar
  13. 13.
    Wensheng L, Yunzhu M A, Baiyun H, Bull Mater Sci 31 (2008) 1.CrossRefGoogle Scholar
  14. 14.
    Bose A, German R M, Powder Metall Int 20 (1989) 9.Google Scholar
  15. 15.
    Penrice T W, and Bost J, US Patent 4762559 (1988).Google Scholar
  16. 16.
    Katavic B, Nikacevic M, and Odanovic Z, Sci Sinter 40 (2008) 319.CrossRefGoogle Scholar
  17. 17.
    Katavic B, Nikacevic M, and Odanovic Z, Powder Metall 48 (2005) 288.CrossRefGoogle Scholar
  18. 18.
    Doepker S P, Mullendore J A, and Spencer J R, Tungsten & Tungsten Alloys, Metal Powder Industries Federation, Princeton (1993).Google Scholar
  19. 19.
    Das J, Kiran U R, Chakraborty A, and Prasad N E, Int J Refract Metals Hard Mater 27 (2009) 577.CrossRefGoogle Scholar
  20. 20.
    Ravi Kiran U, Kumar J, Kumar V, Nageswara Rao G V S, and Nandy T K, Mater Sci Eng A 656 (2016) 256.CrossRefGoogle Scholar
  21. 21.
    Gurland J. Trans AIME 212 (1958) 452.Google Scholar
  22. 22.
    Ravi Kiran U, Panchal A, Sankaranarayana M, Nageswara Rao G V S, and Nandy T K, Mater Sci Eng A 640 (2015) 82.CrossRefGoogle Scholar
  23. 23.
    Stuitje P, Harkerna R, Taal C, Heavy metal alloy and method for its production, US Patent 5462576 (1995).Google Scholar
  24. 24.
    Das J, Appa Rao G, Pabi S K, Sankaranarayana M, and Nandy T K, Mater Sci Eng A 613 (2014) 48.CrossRefGoogle Scholar
  25. 25.
    Dieter G E (ed), Mechanical Metallurgy, McGraw-Hill book Company, London (1988).Google Scholar

Copyright information

© The Indian Institute of Metals - IIM 2017

Authors and Affiliations

  • U. Ravi Kiran
    • 1
  • M. Sankaranarayana
    • 1
  • G. V. S. Nageswara Rao
    • 2
  • T. K. Nandy
    • 1
  1. 1.Defence Metallurgical Research LaboratoryKanchanbagh, HyderabadIndia
  2. 2.National Institute of TechnologyWarangalIndia

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