Microstructures and mechanical properties of pure tantalum processed by high-pressure torsion

Huang, Yi; Maury, Nicolas; Zhang, Nian Xian; Langdon, Terence G.

doi:10.1088/1757-899x/63/1/012100

Cited by 13 publications

(14 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…4 show a large central region of lower hardness after 0.5 turn but this region is gradually removed with further straining so that ultimately, after 10 turns, the central area of lower hardness is exceptionally small. It is important to note also that these colour-coded maps are symmetrical around the central points and this demonstrates that the hardness values recorded from linear traverses along randomly selected diameters, as presented earlier [27], provide a valid representation of the overall behaviour over the disc surface. Furthermore, even though a good level of hardness homogeneity is attained after 10 turns, the results show also that the overall hardness values after 10 turns are slightly lower than the hardness values in the edge areas after 5 turns.…”

Section: Hardness Evolution During Hpt Processingmentioning

confidence: 57%

See 1 more Smart Citation

A critical examination of pure tantalum processed by high-pressure torsion

Maury

Zhang

Huang

et al. 2015

Materials Science and Engineering: A

View full text Add to dashboard Cite

Tantalum, a common refractory metal with body-centred cubic (BCC) crystalline structure, was processed by high-pressure torsion (HPT) at room temperature through different numbers of rotations. Significant grain refinement and high strength were achieved with a reduction in grain size from ~60 m to ~160 nm and an increase in strength from ~200 to >1300 MPa. Hardness measurements revealed a high level of homogeneity after 10 turns of HPT but the hardness after 10 turns was slightly lower than after 5 turns indicating the occurrence of some recovery. Tensile testing at a strain rate of 1.0  10 -3 s -1 gave high strengths of ~1200 MPa but little or no ductility after processing through 1, 5 and 10 turns.The introduction of a short-term (15 min) anneal immediately after HPT processing led to significant ductility in all samples and a reasonable level of strength at ~800 MPa.

show abstract

Section: Hardness Evolution During Hpt Processingmentioning

confidence: 57%

“…Based on these results, the overall objective was to establish a procedure that may be used to enhance the properties of this material for use in bio-applications. An earlier report described some of the preliminary results obtained in this research [27].…”

mentioning

confidence: 75%

A critical examination of pure tantalum processed by high-pressure torsion

Maury

Zhang

Huang

et al. 2015

Materials Science and Engineering: A

View full text Add to dashboard Cite

show abstract

“…Pure tantalum is a BCC material with a relatively high stacking fault energy [37][38][39] making the out of gliding plane movement of dislocations easier.5…”

Section: Resultsmentioning

confidence: 99%

Statistical analysis of dislocations and dislocation boundaries from EBSD data

et al. 2017

View full text Add to dashboard Cite

Electron BackScatter Diffraction (EBSD) is often used for semi-quantitative analysis of dislocations in metals. In general, disorientation is used to assess Geometrically Necessary Dislocations (GNDs) densities. In the present paper, we demonstrate that the use of disorientation can lead to inaccurate results. For example, using the disorientation leads to different GND density in recrystallized grains which cannot be physically justified. The use of disorientation gradients allows accounting for measurement noise and leads to more accurate results. Misorientation gradient is then used to analyze dislocations boundaries following the same principle applied on TEM data before. In previous papers, dislocations boundaries were defined as Geometrically Necessary Boundaries (GNBs) and Incidental Dislocation Boundaries (IDBs). It has been demonstrated in the past, through transmission electron microscopy data, that the probability density distribution of the disorientation of IDBs and GNBs can be described with a linear combination of two Rayleigh functions. Such function can also describe the probability density of disorientation gradient obtained through EBSD data as reported in this paper. This opens the route for determining IDBs and GNBs probability density distribution functions separately from EBSD data, with an increased statistical relevance as compared to TEM data. The method is applied on deformed Tantalum where grains exhibit dislocation boundaries, as observed using electron channeling contrast imaging.

show abstract

“…Microbands have also been reported in tantalum and their existence was mainly associated with the primary slip system in a <111> crystal direction [42]. For bcc metals, such as tantalum, commonly slip occurs in the <111> direction on the planes {110}, {112} and {123}, which are the planes with largest interplanar spacing [28]. The Burgers vector is a/2<111> [43] and these particular screw dislocations control the most of the deformation properties of bcc metals so that in tantalum.…”

Section: Recrystallisation Mechanism and Texturementioning

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

View full text Add to dashboard Cite

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.

show abstract

Microstructures and mechanical properties of pure tantalum processed by high-pressure torsion

Cited by 13 publications

References 31 publications

A critical examination of pure tantalum processed by high-pressure torsion

A critical examination of pure tantalum processed by high-pressure torsion

Statistical analysis of dislocations and dislocation boundaries from EBSD data

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

Contact Info

Product

Resources

About