Laser melting deposition of fine-grained 90 W-7Ni-3Fe alloys using pre-sintered granulated powder

Wei Zhang, Chun Li, Yuzhao Zhou, Xiaoshan Yang, Jiupeng Song, Dou Wang, Yubin Zhang*, Guomin Le*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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Reducing the grain sizes of tungsten (W) in tungsten heavy alloys (WHAs) is pivotal for achieving high strength. Traditional liquid phase sintering (LPS) often results in the growth of W grains, due to the long sintering time and slow cooling rates. To achieve a high cooling rate, a laser melting deposition (LMD) additive manufacturing technique was employed in this study to prepare 90 W-7Ni-3Fe alloys with unique pre-sintered powder prepared using a spray granulation method. The pre-sintered granulated powder particles, each consisting of many fine elemental particles, exhibit a spherical shape with a size up to 100 μm, contributing to optimal flowability. Thin plate samples were prepared using laser powers ranging from 500 W to 900 W. The results show that with laser powers below 600 W, WHAs with fine W grain sizes of 5 μm can be successfully obtained, representing a record of the finest grain size ever reported for the laser additive manufactured WHAs. On the other hand, at 900 W, the W grain size increases significantly to 17 μm, comparable to that of traditional LPS samples. The volume fraction of W grains increases with increasing laser power due to the Ni and Fe evaporation, and at laser power exceeding 700 W, this fraction aligns with 95WNiFe alloys. The fine grains and/or the increased volume fractions of W grains contribute to a higher micro-hardness in these samples compared to LPS samples. Nonetheless, high porosities are also observed in these samples, which leads to a diminished micro-hardness compared to previous LMD 90 W-7Ni-3Fe alloys prepared with mixed elemental powder. This study underscores the potential of the LMD method using pre-sintered powder to fabricate fine-grained WHAs, paving the way for the fabrication of high-strength and high-ductility WHAs using LMD.
Original languageEnglish
Article number106507
JournalInternational Journal of Refractory Metals and Hard Materials
Number of pages6
Publication statusPublished - 2024


  • Fine grain
  • Laser additive manufacturing
  • Pre-sintered powder
  • Tungsten heavy alloy


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