Revisiting the origins of super-hardness in TiB2+z thin films – Impact of growth conditions and anisotropy

Fuger, C.; Hahn, Rainer; Hirle, A.; Kutrowatz, Philip; Weiß, Maximilian; Limbeck, Andreas; Hunold, O.; Polcik, P.; Riedl, H.

doi:10.1016/j.surfcoat.2022.128806

Cited by 17 publications

(5 citation statements)

References 25 publications

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“…UHTCs exhibit high hardness and resistance to corrosion, abrasive and erosive wear 39,40 , thus, are suitable to protect tools and machining components under extreme conditions [41][42][43][44] . Similar to other transition metal diborides, TiB 2 crystallizes in the hexagonal AlB 2 -type phase [45][46][47] (α, P6/mmm) and shows outstanding mechanical properties 48,49 including hardness of 41-53 GPa [50][51][52] . From computational materials science perspective, insights into mechanical behaviour of TiB 2 and other diborides have been offered by ab initio calculations [53][54][55] and recently also by molecular dynamics with classical empirical potentials (TiB 2 56, 57 , ZrB 2 58 , HfB 2 59 ).…”

Section: Introductionmentioning

confidence: 93%

“…Specifically, the [1210] direction exhibits the highest tensile strength (≈ 56 GPa), followed by the [0001] direction (≈ 54 GPa), and the [1010] direction (≈ 51 GPa) xvi . For comparison, the hardness reported for TiB 2 thin films, typically [0001]-textured, is 41-53 GPa [50][51][52] . The [0001] direction exhibits the highest toughness modulus (≈ 4.80 GPa), followed by the [1210] direction (≈ 3.37 GPa), and the [1010] direction (≈ 2.78 GPa) xvii .…”

Section: /18mentioning

confidence: 99%

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Machine-learning potentials for nanoscale simulations of deformation and fracture: example of TiB2 ceramic

Lin,

Casillas-Trujillo,

Tasnadi

et al. 2023

Preprint

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Machine-learning interatomic potentials (MLIPs) offer a powerful avenue for simulations beyond length and timescales of ab initio methods. Their development for investigation of mechanical properties and fracture, however, is far from trivial since extended defects---governing plasticity and crack nucleation in most materials---are too large to be included in the training set. Using TiB2 as a model ceramic material, we propose a strategy for fitting MLIPs suitable to simulate mechanical response of monocrystals until fracture. Our MLIP accurately reproduces ab initio stresses and failure mechanisms during room-temperature uniaxial tensile deformation of TiB2 at the atomic scale (≈103 atoms). More realistic tensile tests (low strain rate, Poisson's contraction) at the nanoscale (≈104--106 atoms) require MLIP up-fitting, i.e. learning from additional ab initio configurations. Consequently, we elucidate trends in theoretical strength, toughness, and crack initiation patterns under different loading directions. To identify useful environments for further up-fitting, i.e., making the MLIP applicable to a wider spectrum of simulations, we assess transferability to other deformation conditions and phases not explicitly trained on.

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Section: Introductionmentioning

confidence: 93%

Section: /18mentioning

confidence: 99%

Machine-learning potentials for nanoscale simulations of deformation and fracture: example of TiB2 ceramic

Lin,

Casillas-Trujillo,

Tasnadi

et al. 2023

Preprint

View full text Add to dashboard Cite

show abstract

“…In contrast, a difference in shear modulus results in a distinct hardness peak attributed to hindered dislocation motion across the interface and within a single layer, as shown for TiB 2 /WB 2 . Nevertheless, the anisotropic properties (predominant [001] texture [14,22]) of hexagonal diborides, combined with the shear modulus differences, need to be considered to interpret the hardness evolution in the case of the TiB 2 /WB 2 system. Additionally, for the TiB 2 /ZrB 2 system, the influence of a possible tissue phase at the absolute values of the fracture toughness-not their progression as the elemental composition is similar throughout the coating series [23].…”

Section: Tablementioning

confidence: 99%

Unraveling the Superlattice Effect for Hexagonal Transition Metal Diboride Coatings

Hahn

Tymoszuk

Wójcik

et al. 2023

Preprint

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“…Two factors may be responsible for the observed decrease in hardness. Fuger et al [41] reported that the extremely high hardness of TiB 2 coatings is strongly associated with a preferential (001) texture. In the case of Ag-free sample 0 W, part of the crystalline TiB 2 phase is preferentially oriented in the (001) direction, and the coating exhibits a hardness of 40 GPa.…”

Section: Mechanical Propertiesmentioning

confidence: 99%

Mechanical and Tribological Properties of Ag/TiBx Nanocomposite Thin Films with Strong Antibacterial Effect Prepared by Magnetron Co-Sputtering

et al. 2023

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The use of silver-based antimicrobial materials has been growing recently. Considering the threat of developing silver-resistant bacteria, it is essential to address the endurance of such materials and the amount of silver released into the environment. Here we report on a durable, antibacterial Ag/TiBx nanocomposite coating prepared by conventional magnetron sputtering. The coating consists of fine Ag clusters embedded in extremely hard, wear-resistant overstoichiometric TiBx, which serves as a protective matrix. The highest E. coli growth inhibition of 97% is observed for the coating containing 24 at.% of Ag. A strong antibacterial effect is also maintained after 45 days of immersion in the Luria–Bertani + 5% HNO3 solution. Despite a marked hardness decrease from 40 GPa for TiBx to 6.4 GPa for Ag/TiBx with 28 at.% of Ag, the coating maintains a good specific wear rate of 6 × 10−5 mm3/Nm. Moreover, the addition of Ag, which acts as a solid lubricant, decreases the coefficient of friction from 0.77 to 0.35, even at room temperature. Thanks to the combination of antibacterial properties and enhanced wear resistance, such material can find application as a protective coating for cutlery, door handles, water taps, and other daily-used objects in public areas.

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Revisiting the origins of super-hardness in TiB2+z thin films – Impact of growth conditions and anisotropy

Cited by 17 publications

References 25 publications

Machine-learning potentials for nanoscale simulations of deformation and fracture: example of TiB2 ceramic

Machine-learning potentials for nanoscale simulations of deformation and fracture: example of TiB2 ceramic

Unraveling the Superlattice Effect for Hexagonal Transition Metal Diboride Coatings

Mechanical and Tribological Properties of Ag/TiBx Nanocomposite Thin Films with Strong Antibacterial Effect Prepared by Magnetron Co-Sputtering

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