Mechanical behavior of high-density nanocrystalline gold prepared by gas deposition method

Sakai, Seiji; Tanimoto, H.; Mizubayashi, H.

doi:10.1016/s1359-6454(98)00339-5

Cited by 86 publications

(58 citation statements)

References 22 publications

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“…8,9) We surmise that some spontaneous reorientation of the ultra-fine particles takes place on the specimen surface just after the landing of the ultra-fine particles, resulting in that the reorientation is completed in the type-L specimens but not in the type-H specimens. The density of the n-Au specimens is the same between the type-L and type-H specimens, but the crystallographic distribution of the constituent n-crystallites is somewhat different between the type-L and type-H specimens.…”

Section: Methodsmentioning

confidence: 91%

“…However, these may be associated with pores contained in the specimens at the dawn of the studies. With progress in the preparation method of n-metal specimens, it is found that the elastic modulus of pore-free or high-density nmetals [6][7][8][9] is very close to that of the conventional polycrystalline (p-) metals. The activation energy found for tracer diffusivity in the high-density n-metals is almost the same as that reported for the GB diffusion in the p-metals.…”

Section: Introductionmentioning

confidence: 89%

“…Figure 1(a) shows an example of the Q À1 observed in n-Au, where a broad peak at around 95 K (Q À1 p,95 K , hereafter) and a steep increase above about 200 K (Q À1 >200 K , hereafter) can be seen. 8) Both Q À1 p,95 K and Q À1 >200 K diminish after the grain growth 9) and remain unchanged after the low temperature irradiation. 21,22) As well as that neither Q À1 p,95 K nor Q À1 >200 K are observed in p-Au, these observations indicate that they are associated with anelastic processes in the GB regions.…”

Section: Introductionmentioning

confidence: 99%

“…These values are compiled in Table 1. Figure 5 shows examples of the tensile tests for the type-H n-Au specimens, 8) where the tensile test at 77 K was interrupted at the strain of 1% to avoid the yielding. To pursue the relaxation parameters for " a-II,>200 K , the stress relaxation tests were conducted.…”

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confidence: 99%

“…5 Examples of the tensile tests for the type-H specimens. 8) Anelasticity Study on Motions of Atoms in the Grain Boundary Regions in Nanocrystalline Gold 55 relaxation curves shown in Fig. 6.…”

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confidence: 99%

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Anelasticity Study on Motions of Atoms in the Grain Boundary Regions in Nanocrystalline Gold

2003

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High-density nanocrystalline (n-) Au was prepared by the gas deposition method. Various anelastic and plastic creep processes associated with the grain boundary (GB) regions were observed. The vibrating reed measurements at 10 2 Hz with strain amplitude of 10 À6 show a very broad internal friction peak near 95 K, Q À1 p,95 K , and a steep increase in the anelastic strain above 200 K, " a-I,>200 K . The tensile tests show a steep increase in the anelastic strain above 200 K, " a-II,>200 K , for the stress beyond a few MPa and a linear plastic creep strain above 200 K, " pc-1 , for stress range between 30 MPa and 150 MPa. The activation parameters, 1= 0 of 3 Â 10 11 s À1 and E of 0.16 eV, are found for Q À1 p,95 K , where 0 and E are a pre-exponential factor and an activation energy of the relaxation time . We surmise that simple relaxation processes are responsible for Q À1 p,95 K . The values of 1= 0 and E found for " a-I,>200 K and " a-II,>200 K decrease with increasing the applied stress or the temperature, indicating that their atomic processes are the same feather. Further, E found for " pc-1 is similar to or slightly smaller than that of " a-II,>200 K . These observations indicate that the atomic motions in the GB regions of n-Au develop in scale in the order of the underlying processes for " a-I,>200 K , " a-II,>200 K and " pc-1 , and are so different from those in the conventional polycrystalline Au.

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Section: Methodsmentioning

confidence: 91%