Mechanical properties of vacuum-deposited metal films—I. Copper films

Henning, C.A.O.; Boswell, F.W.; Corbett, J. M.

doi:10.1016/0001-6160(75)90181-9

Cited by 34 publications

(7 citation statements)

References 13 publications

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“…Moreover, the present flow stresses are within the range of those obtained by Merchant 5 for various EP Cu foils and are in general accord with those for VP Cu foils reported by others. 10,11 The effect of temperature on (a) the strain hardening index ϭ ( 0.10 Ϫ 0.01 )/0.09 normalized with respect to the shear modulus , (b) the fracture stress F , and (c) the fracture strain F are presented in Fig. 7a, b, and c, respectively.…”

Section: Resultsmentioning

confidence: 99%

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Plastic deformation kinetics of electrodeposited Cu foil at low and intermediate homologous temperatures

Conrad

Yang

2002

Journal of Elec Materi

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INTRODUCTIONIn recent years, there has developed a renewed interest in the effect of grain size on the mechanical properties of metals and ceramics with special attention to the submicron grain-size range. In a review 1 by the senior author (HC), it was suggested that the effect of grain size on the flow stress of Cu at low and intermediate homologous temperatures (i.e., T Ͻ 0.5 T M ) could be considered in terms of three grain-size regimes (Fig. 1). Regime I includes grain sizes in the range of approximately 1-100 m, Regime Ia in the range of ϳ0.1-1 m, and Regime II in the range of ϳ0.001-0.1 m. It was concluded that the plastic deformation kinetics in Regimes I and Ia were governed by intragranular dislocation motion. The rate-controlling mechanism in Regime I was deduced to be the intersection of dislocations. The rate-controlling mechanism in Regime Ia appeared to be grain boundary shear induced by dislocation pileups at T Ͻ ϳ350 K and the occurrence of cross slip or the intersection of dislocations at higher temperatures. Grain boundary shear produced by the applied stress alone was proposed to be rate controlling in Regime II.The behavior of polycrystalline Cu with grain size in Regime Ia is of interest in the present paper. The only data in sufficient detail for evaluating the plastic deformation kinetics in this regime known by the present authors are those by Embury and Lahaie (E-L) 2 on 30-m thick, vapor-deposited (VP) Cu foil with a grain size 0.5 Ϯ 0.3 m tested in tension at 77-473 K (Fig. 2). Their results show an irregular variation of the apparent activation volume v = kT ∂ ln ε ⋅ /∂σ with temperature. At T Ͻ ϳ350 K, v increases with decrease in temperature (i.e., with increase in flow stress ), while at T Ͼ 350 K the opposite occurs (i.e., v increases with decrease in ). The latter is the more usual behavior for thermally activated dislocation motion. In the analysis 1 of the E-L data, it was proposed that the rate-controlling mechanism at T Ͻ 350°C was grain boundary shear induced by the pileup of dislocations at the grain boundaries and that at T Ͼ 350 K cross slip or the intersection of dislocations appeared to be the likely mechanism. The objective of the present investiga-The plastic deformation kinetics of electrodeposited (EP) Cu foil (grain size d ϭ 0.6 m) were determined at 296-448 K and compared with those for vapor-deposited (VP) foil (d ϭ 0.5 m) tested at 77-473 K. The apparent activation volume v = kT ∂ ln ε ⋅ /∂σ for both materials exhibited a minimum at ϳ350 K, and at this temperature, there occurred a marked increase in the temperature dependence of the flow stress . The rate-controlling mechanism in both materials at T Ͻ 373 K appears to be grain boundary shear induced by dislocation pileups at the grain boundaries. The results at T ϭ 373-473 K suggest that the dislocation pileups are relieved or prevented and that either cross slip or intersection of dislocations is rate controlling with stronger support for the latter. The determination of the rate-controlling mechanism at the h...

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Section: Resultsmentioning

confidence: 99%

“…Assuming that γ ⋅ 0 is relatively constant, the activation volume v* according to Eq. 6 is (10) or (11) where q = τ ∂ ln γ . /∂τ…”

Section: Intermediate Temperature Regime (T ϭ 373-473 K)mentioning

confidence: 99%

Plastic deformation kinetics of electrodeposited Cu foil at low and intermediate homologous temperatures

Conrad

Yang

2002

Journal of Elec Materi

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“…9-Comparison of the forest dislocation density ratio f / determined from the apparent activation volume v at 300 and 78 K with the total dislocation density / ratios measured by TEM. The pre-exponential for the intersection process is given by [12] where m is the mobile dislocation density, ᐉ* f is the spacing between the forest dislocations, b is the Burgers vector, and v D ϭ 10 13 s Ϫ1 is the Debye frequency. [10] shear-stress activation volume.…”

Section: Plastic-deformation Kineticsmentioning

confidence: 99%

Grain-size dependence of the flow stress of Cu from millimeters to nanometers

Conrad

2004

Metall Mater Trans A

148

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Data in the literature on the effect of grain size (d) from millimeters to nanometers on the flow stress of Cu are evaluated. Three grain-size regimes are identified: regime I, d Ͼ ϳ10 Ϫ6 m; regime II, d Ϸ 10 Ϫ8 to 10 Ϫ6 m; and regime III, d Ͻ ϳ10 Ϫ8 m. Grain-size hardening occurs in regimes I and II; grain-size softening occurs in regime III. The deformation structure in regime I consists of dislocation cells; in regime II, the dislocations are mostly restricted to their slip planes; in regime III, computer simulations indicate that dislocations are absent and that deformation occurs by the shearing of grain-boundary atoms. The transition from regime I to II occurs when the dislocation cell size becomes larger than the grain size, and the transition from regime II to III occurs when the dislocation spacing due to elastic interactions becomes larger than the grain size. The rate-controlling mechanism in regime I is concluded to be the intersection of dislocations; in regime II, it is proposed to be grain-boundary shear promoted by the pileup of dislocations; in regime III, it appears to be grain-boundary shear by the applied stress alone.

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“…28 However, the hardening rate is considerably larger. Simulations for 400 nm films are presented in Figs.…”

Section: B Stress/temperature Hysteresismentioning

confidence: 99%

Stress evolution in passivated thin films of Cu on silica substrates

Shen

Suresh

et al. 1998

J. Mater. Res.

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Stresses supported by thin films of Cu passivated by SiO x have been measured upon thermal cycling. Very high stresses have been found, approaching 1 GPa in the thinnest (40 nm) films. Strengthening beyond yield occurs upon both cooling and heating, indicative of strong strain hardening in the Cu. The hardening continues down to at least 77 K. The yielding behavior of the Cu films has been characterized by a kinematic constitutive law, with exceptional strain hardening and a conventional temperature-dependent yield strength. The physical basis for this behavior is ascribed to confined shear bands in the Cu that induce large back stress. Transmission electron microscopy reveals aligned dislocations, which seemingly dictate the inelastic deformations in the shear bands.

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Mechanical properties of vacuum-deposited metal films—I. Copper films

Cited by 34 publications

References 13 publications

Plastic deformation kinetics of electrodeposited Cu foil at low and intermediate homologous temperatures

Plastic deformation kinetics of electrodeposited Cu foil at low and intermediate homologous temperatures

Grain-size dependence of the flow stress of Cu from millimeters to nanometers

Stress evolution in passivated thin films of Cu on silica substrates

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