Effect of cyclic annealing heat treatment on tungsten particles and matrix interface in heavy tungsten alloy

Document Type : Original Article

Authors

• Ali Harimi ¹
• gholamreza ebrahimi ²
• A Rezaie bazaz ¹
• Hasan Najafi ¹
• kazem Zuichi Turk ²

¹ Department of material science and engineering, Faculty of Engineering, Ferdowsi university of Mashhad, Mashhad, Iran.

² Department of material science and engineering, Faculty of Engineering, Ferdowsi University of Mashhad, Iran.

10.22067/jmme.2024.88925.1151

Abstract

Heavy tungsten alloys are made by liquid phase sintering for application in protective weights, radiation shields, and anti-missiles. The change in each of the production parameters of these alloys affects the mechanical behavior of these alloys. The aim of this research is to assess the effect of annealing heat treatment cyclic on the bonding strength of tungsten particles with the matrix. Tungsten alloy with a chemical composition of 93.5W-5.4Ni-1.95Fe (in wt.%) is first compressed in a plastic mold (cold isostatic) following by liquid phase sintering at 1480 °C and two cycles of annealing heat treatment. In order to study the mechanical properties, tensile and hardness tests are used. Also, the microstructures and fracture surfaces (after tensile test) of the samples are examined using optical and scanning electron microscopes. The obtained results show that due to the thermal stresses during cooling and heating through the cyclic annealing heat treatment, the matrix phase is penetrated into the interface of tungsten particles which causes a decrease in the contiguity (from 0.44 to 0.31). Also, the cyclic annealing heat treatment reduces the impurities in the interface between tungsten particles and the matrix, resulting in an increase in strength (from 842 MPa to 960 MPa). Comparison of fracture surfaces of samples with annealing cyclic shows the change of brittle fracture mechanism to soft fracture. Keywords: Heavy tungsten alloys; Sintering; Heat treatment; Particles/matrix interface; Contiguity.

Keywords

• Heavy tungsten alloys
• particles/matrix interface
• cyclic heat treatment
• sintering
• contiguity

Main Subjects

• Mechanical Metallurgy

---

References

[1] B. C. Muddle, D. V. Edmonds, "Interfacial segregation and embrittlement in liquid phase sintered tungsten alloys" Metal Science, vol. 17, no. 5, pp. 209–218, (1983). https://doi.org/10.1179/030634583790420899.

[2] R. M. German, "Sintered tungsten heavy alloys: Review of microstructure, strength, densification, and distortion" International Journal of Refractory Metals and Hard Materials, vol. 108, no. 105940, pp. 1-20, (2022). https://doi.org/10.1016/j.ijrmhm.2022.105940.

[3] K. S. Churn, R. M. German, "Fracture Behavior of W-Ni-Fe Heavy Alloys" Metallurgical transactions A, vol. 15, no. 2, pp. 331–338, (1984). https://doi.org/10.1007/BF02645119.

[4] M. H. Hong, J. W. Noh, E. P. Kim, H.-S. Song, S. Lee, and W. H. Baek, "A study on the improvement of the sintered density of W-Ni-Mn heavy alloy" Metallurgical and Materials Transactions B, vol. 28, no. 5, pp. 835–839, (1997). https://doi.org/10.1007/s11663-997-0011-9.

[5] R. M. German, Powder Metallurgy Science. 2^nded. Princeton, N.J: Metal Powder Industries Federation, (1994). [E-book] Available: https://lccn.loc.gov/84060862.

[6] R. M German, "Microstructure effects on tensile properties of tungsten-Nickel-Iron composites" Metallurgical Transactions A, vol. 19, no. 6, pp. 1523–1532, (1988).   https://doi.org/10.1007/BF02664666.

[7] C. Lea, B. C. Muddle, D. V. Edmonds, "Segregation to interphase boundaries in liquid-phase sintered tungsten alloys" Metallurgical Transactions A, vol. 14, no. 3, pp. 667–677, (1983). https://doi.org/10.1007/BF02643782.

[8] A. Bose, R. M. German, "Sintering atmosphere effects on tensile properties of heavy alloys" Metallurgical Transactions A, vol. 19, pp. 2467-2476, (1988). https://doi.org/10.1007/BF02645474

[9] L. Ekbom, "Influence of microstructure of liquid-sintered tungsten-base composites on the mechanical properties" Scandinavian Journal of Metallurgy, vol. 5, no. 14, pp. 179–184, (1976). Available: http://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=PASCAL7780098906.

[10] R. M. German, New Tungsten Heavy Alloy Handbook. Metal Powder Industries Federation, (2021). [E-book] Available: https://www.mpif.org.

[11] I. Singh, V. Dabhade. "Tungsten heavy alloys for kinetic energy penetrators: a review" Materials Science and Technology, vol. 40, no. 7-8, pp. 769–785, (2024).‏ https://doi.org/10.1177/02670836241260514.

[12] H. K. Yoon, S. H. Lee, S. J. L. Kang, and D. N. Yoon, "Effect of vacuum-treatment on mechanical properties of W-Ni-Fe heavy alloy" Journal of Materials Science, vol. 18, no. 5, pp. 1374–1380, (1983). https://doi.org/10.1007/BF01111957.

[13] H. S. Song, J. W. Noh, W. H. Baek, S. J. L. Kang, B. S. Chun, "Undulation of W/matrix interface by resintering of cyclically heat-treated W-Ni-Fe heavy alloys" Metallurgical and Materials Transactions A, vol. 28, no. 2, pp. 485–489, (1997). https://doi.org/10.1007/s11661-997-0149-8.

[14] M. E. Alam, G. R. Odette, "The comparative strength and fracture toughness properties of commercial 95W-3.5Ni1.5Fe and 95W-3.5Ni1.5Cu tungsten heavy alloys" Nuclear Materials and Energy, vol. 36, no. 1, pp. 123-135, (2023). https://doi.org/10.1016/j.nme.2023.101467.

[15] J. Das, U. R. Kiran, A. Chakraborty, N. E. Prasad, "Hardness and tensile properties of tungsten based heavy alloys prepared by liquid phase sintering technique" International Journal of Refractory Metals and Hard Materials, vol. 27, no. 3, pp. 577–583, (2009). https://doi.org/10.1016/j.ijrmhm.2008.08.003.

[16] R. M. German, L. L. Bourguignon, B. H. Rabin, "Analysis of high tungsten content heavy alloys" Powder Metallurgy in Defense Technology, vol. 6, pp. 117–131, (1984). https://doi.org/10.1007/BF03257677.

[17] D. V. Edmonds and P. N. Jones, "Interfacial embrittlement in liquid-phase sintered tungsten heavy alloys" Metallurgical Transactions A, vol. 10, no. 3, pp. 289–295, (1979). https://doi.org/10.1007/BF02658336.

[18] W. H. Baek, M. H. Hong, et al. and S. H. Lee, "Heat treatment behavior of tungsten heavy alloy" Solid State Phenomena, vol. 118, pp. 35–40, (2006). https://doi.org/10.4028/www.scientific.net/SSP.118.35.

[19] J. Gurland, "The measurement of grain contiguity in two-phase alloys" Transactions of the Metallurgical Society of AIME, vol. 212, pp. 452–455, (1958). Available: https://cir.nii.ac.jp/crid/1570291225577535488.

[20] U. Ravi Kiran, S. Kumar Khaple, M. Sankaranarayana, G. V. S. S. Nageswara Rao, T. K. Nandy, "Effect of swaging and aging heat treatment on microstructure and mechanical properties of tungsten heavy alloy" Materials Today: Proceedings, vol. 5, no. 2, pp. 3914–3918, (2018). https://doi.org/10.1016/j.matpr.2017.11.647.

[21] J. B. Posthill, M. C. Hogwoodand, D. V Edmonds, "Precipitation at Tungsten/Tungsten Interfaces in Tungsten–Nickel–Iron Heavy Alloys" Powder Metallurgy, vol. 29, no. 1, pp. 45–51, (1986). https://doi.org/10.1179/pom.1986.29.1.45.

[22] U. Ravi Kiran, J. Kumar, V. Kumar, M. Sankaranarayana, G. V. S. Nageswara Rao, T. K. Nandy, "Effect of cyclic heat treatment and swaging on mechanical properties of the tungsten heavy alloys" Materials Science and Engineering: A, vol. 656, pp. 256–265, (2016). https://doi.org/10.1016/j.msea.2016.01.024