Demonstration of an inverse Hall–Petch relationship in electrodeposited nanocrystalline Ni–W alloys through tensile testing

Giga, Akihito; Kimoto, Yoshihisa; Takigawa, Yorinobu; Higashi, Kenji

doi:10.1016/j.scriptamat.2006.03.047

Cited by 145 publications

(55 citation statements)

References 21 publications

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“…16) This trend can be explained from the inverse Hall-Petch relationship reported in the amorphous/nanocrystalline duplex composite. 34,35) In the figure, the maximum peak is located at the position shifted to the advancing side, which is in good agreement with the previous report in crystalline material, 31) and which may be originated from the difference of the material flow between the advancing side and the retreating side. Figure 6 shows the normalized hardness as a function of the volume fraction (V f ) of the crystalline phase for the FSP specimen in this study and those of other BMGs.…”

Section: Resultssupporting

confidence: 91%

Microstructural Change by Friction Stir Processing in Zr-Al-Cu-Ni Bulk Metallic Glass

Takigawa

Kobata

Chung³

et al. 2007

Mater. Trans.

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Microstructural change by friction stir processing (FSP) is examined in Zr-Al-Cu-Ni bulk metallic glass. The microstructure in the friction zone (FZ) exhibits an amorphous ''band-like'' structure, and a small number of nanoscale crystalline particles are observed along the ''band-like'' structure. The change in hardness with the microstructural change is examined and it is revealed that the hardness in FZ greatly increases although the volume fraction of crystalline phase is very limited. The increasing hardness is possibly explained from the combined effect of low temperature annealing during FSP and nano-size of crystalline particles.

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Section: Resultssupporting

confidence: 91%

Microstructural Change by Friction Stir Processing in Zr-Al-Cu-Ni Bulk Metallic Glass

Takigawa

Kobata

Chung³

et al. 2007

Mater. Trans.

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“…'grain size softening' (also called the inverse Hall-Petch relationships) [2]. A number of theories and models have been developed to understand the deviation of the strength from the empirical Hall-Petch equation [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. Recent molecular dynamics (MD) simulations have improved our understanding of the deformation of nanocrystalline materials [13].…”

Section: Introductionmentioning

confidence: 99%

Modeling the dependence of strength on grain sizes in nanocrystalline materials

Bhole

Chen

2008

Science and Technology of Advanced Materials

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A model was developed to describe the grain size dependence of hardness (or strength) in nanocrystalline materials by combining the Hall-Petch relationship for larger grains with a coherent polycrystal model for nanoscale grains and introducing a log-normal distribution of grain sizes. The transition from the Hall-Petch relationship to the coherent polycrystal mechanism was shown to be a gradual process. The hardness in the nanoscale regime was observed to increase with decreasing grain boundary affected zone (or effective grain boundary thickness, ) in the form of −1/2 . The critical grain size increased linearly with increasing . The variation of the calculated hardness value with the grain size was observed to be in agreement with the experimental data reported in the literature.

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“…The mechanical, magnetic and electrical properties of the nanocrystalline materials sometimes break the conventional scaling laws. For instance, many studies have reported that the hardness 4) (or yield strength 5) ) peaks out at the grain size of around a dozen nanometers before reaching amorphous limit, termed HallPetch breakdown. Similar trend is true for the coercivity of nanocrystalline ferromagnetic alloys.…”

Section: Introductionmentioning

confidence: 99%

Ni-W Amorphous/Nanocrystalline Duplex Composite Produced by Electrodeposition

et al. 2007

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Detailed characterizations are performed to identify the nanostructures of electrodeposited Ni-W alloys with grain size of 5 and 8 nm. Three-dimensional atom probe (3DAP) analyses have clarified that, in both alloys, experimentally measured W-concentration distributions fit well to the bimodal binomial distribution compared to the single binomial distribution. This result indicates the coexistence of W-depleted and W-enriched phases in the alloys. Nano-beam diffraction (NBD) patterns and energy dispersive x-ray spectroscopy (EDS) analyses revealed that the W-enriched phase is amorphous and that the W-depleted phase is nanocrystalline. The W-concentration visualizations on the cross section of 3DAP analysis volume identify them as amorphous/nanocrystalline duplex composites.

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Demonstration of an inverse Hall–Petch relationship in electrodeposited nanocrystalline Ni–W alloys through tensile testing

Cited by 145 publications

References 21 publications

Microstructural Change by Friction Stir Processing in Zr-Al-Cu-Ni Bulk Metallic Glass

Microstructural Change by Friction Stir Processing in Zr-Al-Cu-Ni Bulk Metallic Glass

Modeling the dependence of strength on grain sizes in nanocrystalline materials

Ni-W Amorphous/Nanocrystalline Duplex Composite Produced by Electrodeposition

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