On the solid solution hardening of tantalum by nitrogen and oxygen

Puhr-Westerheide, J.; Elssner, G.

doi:10.1016/0022-5088(70)90013-5

Cited by 23 publications

(9 citation statements)

References 9 publications

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“…The higher the content of oxygen, the higher the resulting average hardness value. This agrees with what found in the literature [19]; in particular, nitrogen and oxygen are strong hardeners of unalloyed polycrystalline tantalum. In the work of Stecura [29], the hardness of tantalum increased almost linearly when increasing oxygen content in solid solution.…”

Section: Hardnesssupporting

confidence: 93%

“…The major contribution to the high yield strength of the deposited structures was given by the higher content of oxygen. As already reported in the literature, the yield stress increases linearly with increasing amounts of nitrogen or oxygen [19]. This can also be seen when comparing the yield strength of A2 over B2 in both testing directions (Fig.…”

Section: Tensile Propertiessupporting

confidence: 87%

“…It is important to note that the raw materials used in this study had a concentration of 0.18 wt.% of oxygen. These oxygen levels are considerably high, and it is known that oxygen leads to strengthening in the tantalum components [19]. In the work of Thijs et al [20], the LPBF process was studied for tantalum, focusing mainly on the microstructural evolution and mechanical properties.…”

Section: Introductionmentioning

confidence: 99%

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Microstructure, hardness and mechanical properties of two different unalloyed tantalum wires deposited via wire + arc additive manufacture

Marinelli

Martina

Ganguly

et al. 2019

International Journal of Refractory Metals and Hard Materials

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An innovative way of producing large-scale unalloyed tantalum parts, based on the Wire + Arc Additive Manufacturing process, has been developed in this study. Two different unalloyed tantalum wires have been used to deposit 200-mm-long structures in tantalum. The effect of the wire chemistry on microstructure, hardness, porosity, mechanical properties and strain localisation has been investigated. The deposits showed high integrity and excellent mechanical properties, with yield strength, ultimate tensile strength and elongation as high as 234 MPa, 261 MPa, and 36 %, respectively. Indeed, yield strength was higher than commercially available tantalum, even though, in this study, the grains were large and had a high aspect ratio. Wire + Arc Additive Manufacture has clearly shown the potential to produce tantalum components with relatively low cost and reduced lead time, thus offering a new robust and viable manufacturing route.

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Section: Hardnesssupporting

confidence: 93%

Section: Tensile Propertiessupporting

confidence: 87%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Microstructure, hardness and mechanical properties of two different unalloyed tantalum wires deposited via wire + arc additive manufacture

Marinelli

Martina

Ganguly

et al. 2019

International Journal of Refractory Metals and Hard Materials

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“…17) Lachenmann and Schultz showed that in Ta-N solid solution single crystals, the shear yield stress at room temperature increases linearly with N concentration (below 0.04 at%) with the rate of 500 MPa/ at% N. 19) Puhr-Westerheide and Elssner reported that yield stress of polycrystalline Ta increases linearly with O concentration and N concentration (below 1.0 at%) with the rate of ¦·/¦c = 630 MPa/at% and 400 MPa/at%, respectively. 20) No data are available for interstitial solution hardening for bcc Ti-based alloys, but the shear yield stress at room temperature, 280 MPa for 1.2 at% oxygen, may well be interpreted mainly by interstitial solution hardening.…”

Section: )mentioning

confidence: 99%

Thermally Activated Deformation of Gum Metal: A Strong Evidence for the Peierls Mechanism of Deformation

et al. 2015

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Compression deformation and stress relaxation tests have been made over a wide temperature range for Ti-based bcc alloy single crystal of Gum Metal composition to elucidate the deformation mechanism. The shear yield stress decreases rapidly with increasing temperature with decreasing slope above room temperature, tending to level off. Activation analysis showed that the activation volume becomes smaller than 10 b 3 (b: the Burgers vector) at high stress, indicating that the deformation is controlled by the Peierls mechanism at low temperature. Similar results have been obtained also for severely cold-swaged polycrystalline Gum Metal with the similar composition. These results contradict the generally accepted dislocation-free mechanism of Gum Metal.

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“…The dislocation densities associated with these values of hardness should result to be respectively 5x10 14 m -2 and 1.2x10 15 This equation does not take into account the effect of interstitials on the hardness in tantalum. In fact, it is known that nitrogen and oxygen are strong hardeners of unalloyed polycrystalline tantalum [39]. In the work of Stecura [40], it is shown that the hardness of tantalum increased almost linearly when increasing oxygen content in solid solution.…”

Section: Dislocations Density and Oxygen Contentmentioning

confidence: 99%

Grain refinement in an unalloyed tantalum structure by combining Wire+Arc additive manufacturing and vertical cold rolling

Marinelli

Martina

Ganguly

et al. 2020

Additive Manufacturing

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Components manufactured via Wire + Arc Additive Manufacturing are usually characterised by large columnar grains. This can be mitigated by introducing in-process cold-rolling; in fact, the associated local plastic deformation leads to a reduction of distortion and residual stresses, and to microstructural refinement. In this research, interpass rolling was applied with a load of 50 kN to a tantalum linear structure to assess its effectiveness in changing the grain structure from columnar to equiaxed, as well as in refining the grain size. An average grain size of 650 µm has been obtained after five cycles of inter-pass rolling and deposition. When the deformed layer was reheated during the subsequent deposition, recrystallisation occurred, leading to the growth of new strain-free finer equiaxed grains. The depth of the refined region has been characterised and correlated to the hardness profile developed after rolling. A reduction of porosity was also registered. Furthermore, a random texture was formed after rolling, which should result in isotropic mechanical properties. Wire + Arc Additive Manufacturing process demonstrated the ability to deposit sound refractory metal components and the possibility to improve the microstructure when coupled with cold inter-pass rolling.

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On the solid solution hardening of tantalum by nitrogen and oxygen

Cited by 23 publications

References 9 publications

Microstructure, hardness and mechanical properties of two different unalloyed tantalum wires deposited via wire + arc additive manufacture

Microstructure, hardness and mechanical properties of two different unalloyed tantalum wires deposited via wire + arc additive manufacture

Thermally Activated Deformation of Gum Metal: A Strong Evidence for the Peierls Mechanism of Deformation

Grain refinement in an unalloyed tantalum structure by combining Wire+Arc additive manufacturing and vertical cold rolling

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