The effect of a small addition of boron on the sintering densification, microstructure and mechanical properties of powder metallurgy Ti-7Ni alloy

Luo, S. D., Yang, Y. F., Schaffer, G. B. and Qian, M. (2013) The effect of a small addition of boron on the sintering densification, microstructure and mechanical properties of powder metallurgy Ti-7Ni alloy. Journal of Alloys and Compounds, 555 339-346. doi:10.1016/j.jallcom.2012.12.068


Author Luo, S. D.
Yang, Y. F.
Schaffer, G. B.
Qian, M.
Title The effect of a small addition of boron on the sintering densification, microstructure and mechanical properties of powder metallurgy Ti-7Ni alloy
Journal name Journal of Alloys and Compounds   Check publisher's open access policy
ISSN 0925-8388
1873-4669
Publication date 2013-04-05
Year available 2012
Sub-type Article (original research)
DOI 10.1016/j.jallcom.2012.12.068
Open Access Status Not yet assessed
Volume 555
Start page 339
End page 346
Total pages 8
Place of publication Amsterdam, Netherlands
Publisher Elsevier
Language eng
Subject 2210 Mechanical Engineering
2211 Mechanics of Materials
2505 Materials Chemistry
2506 Metals and Alloys
Abstract The effect of a small addition of boron (B) on the sintering, sintered microstructure and mechanical properties of a Ti-7Ni alloy (wt.%) compacted from -100 mesh hydride-dehydride (HDH) Ti powder has been investigated systematically. An addition of ≥0.62%B to the Ti-7Ni alloy resulted in fast, near full-densification (≥99% relative density) within 15 min at 1200 °C, compared to 95.6% relative density obtained after 120 min at 1200 °C without B, compacted at 400 MPa in both cases. In addition, the pre-eutectoid α phase changed from long parallel α-laths (up to ∼500 μm) to near-equiaxed α-Ti throughout the microstructure with an addition of ≥0.31%B. Elemental B was found to be more effective than TiB as a sintering aid for Ti-7Ni. A small addition of B increased both the tensile strength and yield strength of Ti-7Ni but at the expense of tensile ductility. The mechanisms behind each of these observations were discussed.
Formatted abstract
The effect of a small addition of boron (B) on the sintering, sintered microstructure and mechanical properties of a Ti-7Ni alloy (wt.%) compacted from −100 mesh hydride-dehydride (HDH) Ti powder has been investigated systematically. An addition of ⩾0.62%B to the Ti–7Ni alloy resulted in fast, near full-densification (⩾99% relative density) within 15 min at 1200 °C, compared to 95.6% relative density obtained after 120 min at 1200 °C without B, compacted at 400 MPa in both cases. In addition, the pre-eutectoid α phase changed from long parallel α-laths (up to ∼500 μm) to near-equiaxed α-Ti throughout the microstructure with an addition of ⩾0.31%B. Elemental B was found to be more effective than TiB2 as a sintering aid for Ti-7Ni. A small addition of B increased both the tensile strength and yield strength of Ti–7Ni but at the expense of tensile ductility. The mechanisms behind each of these observations were discussed.
Keyword Titanium alloys
Powder metallurgy
Boron
Refinement
Modification
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Published online 23 December 2012.

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Mechanical & Mining Engineering Publications
Official 2013 Collection
 
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