Fabrication and mechanical properties of powder metallurgy tantalum prepared by hot isostatic pressing

The fabrication process of a powder metallurgy (P/M) tantalum product with full density and fine microstructure was developed by using cold and hot isostatic pressing techniques. In order to increase the compact density and make the uniform density distribution, cold isostatic pressing (CIPing) of t...

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Bibliographic Details
Published in:International journal of refractory metals & hard materials 2015-01, Vol.48, p.211-216
Main Authors: Kim, Youngmoo, Kim, Eun-Pyo, Noh, Joon-Woong, Lee, Sung Ho, Kwon, Young-Sam, Oh, In Seok
Format: Article
Language:English
Subjects:
Billets
Densification
Density
Hot isostatic pressing
Mechanical properties
Mechanical property
Microstructure
Powder metallurgy
Tantalum
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Summary:The fabrication process of a powder metallurgy (P/M) tantalum product with full density and fine microstructure was developed by using cold and hot isostatic pressing techniques. In order to increase the compact density and make the uniform density distribution, cold isostatic pressing (CIPing) of tantalum powders was conducted. Prior to hot isostatic pressing (HIPing), the CIPed billet was encapsulated and degassed to remove the contaminants in the container. After degassing, HIPing was performed twice and full densification of the tantalum powders was accomplished, regardless of powder size. The effect of processing conditions on the microstructure and mechanical properties of P/M tantalum billets was investigated. As the number of processing steps and temperature increased, the grain size of HIPed tantalum billets increased. Moreover, contrary to the Hall–Petch relation, the mechanical strength was increased in spite of increasing the grain size. This is because the oxygen content of the billets increased with rising in temperature and the number of processing steps. Therefore, in case of tantalum, it is found that the mechanical properties of tantalum may be highly influenced by the amount of interstitial elements, especially oxygen, rather than microstructural properties. •The sintering behavior and microstructural evolution of tantalum powders were investigated.•The mechanical properties of P/M tantalum were measured and compared with previous results.•The properties may be influenced by the oxygen content rather than microstructures.
ISSN:0263-4368
2213-3917
DOI:10.1016/j.ijrmhm.2014.09.012