Structure and properties of tantalum carbide crystals

Rowcliffe, D. J.; Warren, W. J.

doi:10.1007/pl00020109

Cited by 44 publications

(15 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Previous studies have shown that: B1-structured TMCs and TMNs are more metallic than ionic in nature; 112,113 the nature and relative strengths of metal-metal and metal-carbon (or metal-nitrogen in case of TMNs) bonds vary with the valence electron concentration in the lattice 14,17 and covalent radii of the metal cations; and their mechanical properties are sensitive to anion-vacancy concentration and the type of metal cation. 18,[35][36][37]39 Recently, pseudobinary TMN alloys with enhanced toughness have been designed and synthesized by choosing alloying elements with optimal valence electron concentrations. [8][9][10] The same principles can also be applied to design TMCs with superior room-temperature plasticity.…”

Section: (6) Design Of Tough Tmcsmentioning

confidence: 99%

“…[18][19][20][21] These TMCs (and TMNs of similar structure) are technologically important and are used in a wide variety of applications: as catalysts, 22,23 as hard and decorative coatings, [24][25][26] as metallic interconnects and diffusion barriers in electronics, and as high-temperature structural components in aerospace vehicles. 27,28 Existing literature, 18,20,[29][30][31][32][33][34][35][36][37][38][39][40][41][42][43] dating back to 1960s, indicates that TMCs deform plastically at high temperatures. Among these reports, simple experiments by Lee and Haggerty 31 beautifully illustrate the role of crystalline anisotropy (or lack thereof) on mechanical behavior of ZrC, a group IV TMC.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Nanomechanics of Refractory Transition‐Metal Carbides: A Path to Discovering Plasticity in Hard Ceramics

2015

View full text Add to dashboard Cite

Refractory carbides of transition metals (Zr, Ta, etc.), owing to a mixture of ionic, covalent, and metallic bonding, exhibit high hardness (10s of GPa), high elastic moduli (100s of GPa), good resistance to wear, ablation, and corrosion, high‐temperature mechanical strength, along with good electrical conductivities. They are attractive as high‐temperature structural components in aerospace vehicles. Although these materials are exceptionally hard, their structural applications at low temperatures have been limited because of their brittleness. The design of ceramic materials possessing both high hardness and enhanced ductility has been a long‐standing challenge. Various research studies have focused on this topic with limited success. Here, we present a brief review of our recent results obtained from direct observations of mechanical deformation during uniaxial compression of group IV and group V transition‐metal carbide (ZrC and TaC) single crystals inside a transmission electron microscope. Our studies provide new insights into the mechanical deformation mechanisms and help to identify strategies for enhancing room‐temperature plasticity in this class of materials.

show abstract

Section: (6) Design Of Tough Tmcsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Nanomechanics of Refractory Transition‐Metal Carbides: A Path to Discovering Plasticity in Hard Ceramics

2015

View full text Add to dashboard Cite

show abstract

“…TaC can be prepared [52] by heating Ta and C together at 1850°C for a total period of 9 h; Rowcliffe and Warren prepared TaC by heating at 2200°C for 1 h [53]. Heating Ta powder and carbon nanotubes for long times at lower temperature (780°C for 48 h) produced a mixture of TaC and Ta 2 C. A particularly important result of the latter study was that the hcp phase Ta 2 C forms first, as expected from the TaC phase diagram [54].…”

Section: Discussionmentioning

confidence: 99%

Observations of fcc and hcp tantalum

et al. 2015

View full text Add to dashboard Cite

The metal tantalum has many varied uses including in microelectronics (especially in capacitors) as thin films, in medical applications as an implant material or for surgical instruments, in X-ray lithography for masks, and in high-temperature structural applications. Ta is particularly useful because it is relatively ductile, refractory in nature, and does not readily react with corrosive materials. The body-centered cubic (bcc) crystal structure of pure Ta, also known as the a-phase, is the most commonly observed, but Ta is also known to exist in two other allotropes, one tetragonal and the other (much less-wellknown) face-centered cubic (fcc). The tetragonal form (bTa) has been produced by various deposition techniques and often occurs mixed with the a-phase; the fcc phase has only previously been reported in thin films deposited by thermal evaporation. There have been other reports of 'bcc metals' such as V and Fe existing with an fcc crystal structure when the metal is deposited as a thin film. In the present study, fcc Ta with a = 0.43 nm has been observed using transmission electron microscopy in bulk samples of Ta that have been subjected to quasi-static tensile deformation that was so large as to cause fracture of the material. The fcc phase has a relatively small grain size but appears to be stable at room temperature. It is also shown that relatively large grains (10-20 nm in diameter) of Ta can also exist with an hcp structure with a = 0.304 nm and c = 0.494 nm.

show abstract

“…One reason for this discrepancy could be the non-stoichiometric TaC that is normally investigated [40]. When non-stoichiometric tantalum carbide like TaC 0.83 is studied, the electronic configuration in p and d orbital varies in a way that the covalent bonding increases at the expense of metallic bonding, strengthening the interatomic bonds and as a consequence the hardness and melting point increase [40].…”

Section: Thermodynamic Stabilitymentioning

confidence: 99%