Structure transformations and superhardness effects in V/Ti nanostructured multilayers

Xu, Jie; Kamiko, Masao; Zhou, Yaomin; Lü, Guang-Hong; Yamamoto, Ryōichi; Yu, Lihua; Kojima, Isao

doi:10.1063/1.1500435

Cited by 34 publications

(21 citation statements)

References 14 publications

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“…7,8,21,22 But in Pd/Ti multilayer films, the interfaces are very sharp because metallic Pd and Ti are mutually immiscible. Second, The hardness enhancement calculated using three-dimensional stress fields will be larger than that of the one-dimensional stress fields that are the real stress state in the Pd/Ti multilayers.…”

Section: Discussionmentioning

confidence: 99%

Structure, hardness, and elastic modulus of Pd/Ti nanostructured multilayer films

Xu¹,

Kamiko²,

Sawada³

et al. 2003

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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Articles you may be interested inWorking pressure induced structural and mechanical properties of nanoscale Zr N ∕ W 2 N multilayered coatings J. Vac. Sci. Technol. A 24, 966 (2006); 10.1116/1.2202124 Coherent growth and mechanical properties of AlN/VN multilayers J. Appl. Phys. 95, 92 (2004); 10.1063/1.1630367Formation of metastable c-AlN and its effect on the mechanical properties of AlN/(Ti,Al)N nanoscale multilayers Mechanical properties, stress evolution and high-temperature thermal stability of nanolayered Mo-Si-N/SiC thin films J.The structure, hardness, and elastic modulus of Pd/Ti multilayers deposited by radio-frequency magnetron sputtering were investigated by x-ray diffraction, high-resolution transmission electron microscopy, and nanoindentation. Both the Ti and Pd layers were face-centered-cubic structures in all modulation periods from 2.8 nm to 90.0 nm in Pd/Ti multilayers. There are stacking faults in Ti layers at large modulation periods, where the crystal structure is hexagonal close packed. An anomalous hardness enhancement was observed. The hardness values of Pd/Ti multilayers are three times and two times the values measured in Pd films and as calculated by the rule of mixture for Pd and Ti films, respectively. The modulus values of Pd/Ti multilayers are between those of constituent single layer films at a larger modulation period, and increase slightly at a smaller modulation period. The elastic modulus difference model cannot explain this hardness enhancement, since the elastic modulus is almost the same for the constituent materials in the Pd/Ti multilayers. The hardening mechanisms in the multilayers have been discussed.

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Section: Discussionmentioning

confidence: 99%

Structure, hardness, and elastic modulus of Pd/Ti nanostructured multilayer films

Xu¹,

Kamiko²,

Sawada³

et al. 2003

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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“…This increase arises from image forces on dislocations due to a shear modulus difference between the layers. Other theories that tries to explain the observed increase in hardness are, coherency stress hardening [4][5][6] , where dislocation movement is restricted by the stress fields present at coherent interfaces within the multilayer. Also, the epitaxial stabilization effect has been demonstrated 7 , where a metastable structure for one of the layer materials is formed by pseudomorphic forces to the surface of the other layer during nucleation and growth thus creating a coherent interface, e.g., a normally amorphous material assuming crystalline structure for small layer thicknesses.…”

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Nanostructure formation during deposition of TiN∕SiNx nanomultilayer films by reactive dual magnetron sputtering

Söderberg

Odén

Molina-Aldareguia

et al. 2005

Journal of Applied Physics

150

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Growth of multilayer or superlattice thin films has shown various degrees of hardness enhancements often exceeding the individual hardness of the materials involved. Typically the hardness increases with decreasing wavelength until a maximum value is reached in the nm range, after which the hardness decreases with further decrease in wavelength 1,2 . Different theories have been developed in order to explain the observed increase in hardness. Koehler 3 showed theoretically a hardness increase for materials with a lamellar structure. This increase arises from image forces on dislocations due to a shear modulus difference between the layers. Other theories that tries to explain the observed increase in hardness are, coherency stress hardening 4-6 , where dislocation movement is restricted by the stress fields present at coherent interfaces within the multilayer. Also, the epitaxial stabilization effect has been demonstrated 7 , where a metastable structure for one of the layer materials is formed by pseudomorphic forces to the surface of the other layer during nucleation and growth thus creating a coherent interface, e.g., a normally amorphous material assuming crystalline structure for small layer thicknesses. For Orowan-like strengthening 8-11 , plastic deformation occurs by dislocation movement and bowing inside layers. Finally, in the case of Hall-Petch strengthening 12-13 hardness increases due to a reduction in grain size and thereby an increase in grain boundary density, grain boundaries which acts as dislocation obstacles.Multilayer thin films consisting of titanium nitride (TiN) and silicon nitride (Si 3 N 4 ) layers with compositional modulation periodicities between 3.7 and 101.7 nm have been grown on silicon wafers using reactive magnetron sputtering. Electron microscopy and X-ray diffraction studies showed that the layering is flat with distinct interfaces. According to the XRD studies (figure 1), the deposited TiN layers were crystalline and exhibited a preferred 002 orientation for layer thicknesses of 4.5 nm and below. For larger TiN layer thicknesses, a mixed 111/002 preferred orientation was present as the competitive growth favored 111 texture in monolithic TiN films. The TEM studies (figure 2) revealed that the Si 3 N 4 layers exhibited amorphous structure for layer thicknesses ≥ 0.8 nm, however, for the first time cubic crystalline silicon nitride phase was observed for layer thicknesses ≤ 0.3 nm. Formation of this metastable SiN x phase is explained by epitaxial stabilization to TiN. The microstructure of the multilayers displayed columnar growth within the TiN layers with intermittent TiN renucleation after each Si 3 N 4 layer. A nano-brick-wall structure was thus demonstrated over a range of periodicities. As-deposited films exhibited relatively constant residual stress levels of 1.3±0.7 GPa (compressive) independent of the layering. Nanoindentation was used to determine the hardness of the films, and the measurements showed an increase in hardness for the multilayered films compared to the ...

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“…[1][2][3][4] These properties are generally attributed to the fact that, as the layer thicknesses decrease, the individual layer behavior changes and the interface volume in the material increases. NMMs have displayed many attractive properties, such as high strength, radiation damage resistance, and corrosion damage resistance.…”

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confidence: 99%

Load Sharing Phenomena in Nanoscale Cu/Nb Multilayers

et al. 2014

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Structure transformations and superhardness effects in V/Ti nanostructured multilayers

Cited by 34 publications

References 14 publications

Structure, hardness, and elastic modulus of Pd/Ti nanostructured multilayer films

Structure, hardness, and elastic modulus of Pd/Ti nanostructured multilayer films

Nanostructure formation during deposition of TiN∕SiNx nanomultilayer films by reactive dual magnetron sputtering

Load Sharing Phenomena in Nanoscale Cu/Nb Multilayers

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