Supraleitung und Teilchengr��e in heterogenen Kupfer-Blei-Legierungen

Raub, Ch.J.; Raub, Ernst

doi:10.1007/bf01383948

Cited by 94 publications

(142 citation statements)

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“…The maximum solid solubility of Au in ␦-Fe was found to be 2.3 at% at 1431°C and in ␥-Fe 4.1 at% at 1171°C. The solid solubility data of Au in ␣-Fe for the temperature range 500-903°C are taken from X-ray measurements of [9] and are in a good agreement with values reported by [13]. The reported solid solubilities of Au at 500°C were 0.14 at% [9] and 0.1 at% [13], respectively.…”

Section: Fe-au Phase Diagramsupporting

confidence: 77%

“…Interestingly, among a large number of existing binary Au diagrams only the Fe-Au diagram met the requirement. Figure 2 represents the phase relationships in the system Fe-Au, constructed from data reported in the literature [7][8][9][10][11][12][13]. The diagram is based mainly on experimental results obtained by Raub and Walter [9] and Buckley and HumeRothery [12].…”

Section: Fe-au Phase Diagrammentioning

confidence: 99%

“…Fe-rich part of the Fe-Au binary phase diagram at 903°C [9]. Considering the ␥-Fe ➝ ␣-Fe + Au eutectoid reaction, the data are rather scarce.…”

Section: Figurementioning

confidence: 99%

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Gold nanostructures by directional solid-state decomposition

2006

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The trend in electronics industry towards miniaturisation is leading to increasing research focus on nano-electronic devices. For example, metal nanowires show potential for future application as connector lines in such devices. The controlled fabrication of these structures at scales beyond the current limits of lithographic techniques is of great interest. Self-assembly processes using gold nanoparticles are being extensively studied as one possible long-term solution. This study addresses a novel approach of obtaining gold nanostructures. It consists of applying directional solidification processing to eutectoid alloys in order to produce ordered structures, followed by phase separation by selective etching.The directional transformation of eutectoid alloys is a close derivation of the directional solidification of eutectics. In this case, two phases precipitate simultaneously from a high-temperature solid phase (Figure 1). When the growth properties of the two phases are sufficiently compatible, unidirectional decomposition can also produce aligned composite materials [1,2]. One of the most prominent examples of eutectoid reaction is the formation of pearlite by undercooling a Fe-C alloy in the ␥-state. Microstructures are best when the high-temperature phase is nearly singlecrystalline. Therefore, aligned eutectoids are often produced by accomplishing unidirectional solidification and unidirectional decomposition sequentially. Eutectic solidification and eutectoid decomposition, as examples of duplex crystal growth, are inherently more complex than single-phase crystal growth. The technique used in both cases is quite similar: a specimen is unidirectionally translated through a steep temperature gradient and traversed by a macroscopically planar transformation front. If adequate experimental conditions are arranged, the eutectoid reaction product is an aligned microstructure. The conditions to be met are: i) sufficiently steep gradient to avoid both nucleation before the actual position of the transformation front and coalescence afterwards, ii) a translation rate which permits the attainment of a transformation front with stationary moving conditions, i.e., as a first approximation, a lower translation rate than the maximum eutectoid growth rate.Although eutectic and eutectoid reactions are essentially the same in nature, there are some differences that must be pointed out. Firstly, eutectoid spacings are much finer than the eutectic spacings for the same growth rate, due to the lower values of diffusion coefficients in the solid state as compared to the liquid. Also, a decrease in eutectoid spacing, , with increasing growth rate, V, is generally slower for eutectoids than for eutectics. Data can again be fitted to a formula n V = const. However, whereas n = 2 fits to almost all data for eutectics, values of n ranging from 2 to 4 have been reported for eutectoids. The value n = 2 is consistent with volume-diffusion control, and n = 3 is predicted for grain-boundary-diffusion control.

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Section: Fe-au Phase Diagramsupporting

confidence: 77%

Section: Fe-au Phase Diagrammentioning

confidence: 99%

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Gold nanostructures by directional solid-state decomposition

2006

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“…Since the precipitate density is low near the grain boundary in the Cu-Zr-Cr alloy, the precipitates dissolve into the grain boundary during grain growth as in the Cu-Cr alloy, and the precipitates on the grain boundary obstruct the grain boundary migration as shown in Photo. 8 V. Conclusions…”

Section: Recrystallisation Of Supersaturated Solid Solutionmentioning

confidence: 95%

“…According to this review, the recrystallisation of supersaturated solid solutions can be classified into: (1) recrystallisation which is driven by discontinuous precipitation, that is, the main driving force for recrystallisation is the chemical driving force of the so-called grain boundary reaction, e. g. in Cu-Be alloy(11)(12), Ni-Be alloy(13) and Fe-Ni-Cr-Ti alloy (14), etc., and (2) recrystallisation which is driven by release of stored energy by dislocation annhilation, and is obstructed by fine precipitates, e. g. in Al-Fe alloy(15), Cu-Co alloy(16), Ni-Al alloy (17) and Nb-Ag permalloy (8). It can be seen that the classification is substantially deduced from the phase diagrams for the alloy systems.…”

Section: Recrystallisation Of Supersaturated Solid Solutionmentioning

confidence: 97%

Effect of Precipitates on Recrystallisation Temperature in Cu–Cr, Cu–Zr and Cu–Zr–Cr Alloys

et al. 1973

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In a previous paper, it was reported that the high recrystallisation temperature of Cu-Cr, Cu-Zr and Cu-Zr-Cr alloys was due to the formation of fine precipitates during recrystallisation, which obstructed dislocation climb, glide and grain boundary migration. In the present paper, the recrystallisation behaviours in Cu-Cr, Cu-Zr and Cu Zr-Cr alloys quenched, tempered metric method, measurements of mechanical properties and transmission electron microscopy. No fine precipitates were detected at dislocations or sub-boundaries in the low temperature annealing stage, but fine precipitates, which retard recovery, must exist since electrical resistivity decreased during low temperature annealing. The mechanism of retardation of recovery is due to the binding of dislocation jogs by fine precipitates. In the high annealing temperature range, the growth of precipitates and crystal grains was observed by transmission electron microscopy and the effect of precipitates on the retardation of recrystallisation was also detected. The size of precipitates formed during tempering before cold working did not affect the recrystallisation temperature, because the precipitates were broken up by heavy cold work and were thus made a constant size.

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