Effect of minor elements addition on glass formation and properties of gold alloys

Fiore, Gianluca; Ichim, Ioana Mihaela; Battezzati, Livio

doi:10.1088/1742-6596/144/1/012039

Cited by 6 publications

(7 citation statements)

References 9 publications

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“…No XRD reflection could be seen and assigned to them, possibly because of their low amount. From analogy with previous studies [15] they are identified as Ti 5 Si 3 . Confirmation of the difference in microstructure between the two sides comes from crystallisation studies of the alloys.…”

Section: Resultsmentioning

confidence: 67%

“…Volume diffusion can also be envisaged for letting the gold emerge to the surface, but it is less likely to be effective: in fact, it should cause the formation of crystallisation products of the alloy (i.e. gold silicides [15]), at least temporarily, in the bulk which have never been found here, not even occasionally. At last, it is possible to exclude the dissolution/re-deposition mechanism because, under the applied electrochemical condition, gold does not dissolve or dissolve very slowly.…”

Section: Discussionmentioning

confidence: 99%

“…It has been recently shown that the addition of Ti, having a strongly negative heat of mixing with Au and Si, improves the glass forming ability of the ternary system, although the resulting alloy is not a bulk glass former [14,15]. Ribbons were obtained with the Au 42 Cu 29 Ti 8 Si 21 and Au 44 Cu 31 Ti 4 Si 21 compositions closer to the parting limit for dealloying than previous cases.…”

Section: Introductionmentioning

confidence: 88%

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Dealloying of an Au-based amorphous alloy

2010

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a b s t r a c tThe dealloying behaviour of Au 42 Cu 29 Ti 8 Si 21 and Au 44 Cu 31 Ti 4 Si 21 amorphous (wheel-side) and partially crystalline (air-side) ribbons was investigated using potentiostatic and galvanostatic etching. The resulting microstructures are: i) on the wheel-side homogeneous porosity with size from tens of nanometers to less than 1 mm in between Au crystals is largely found, ii) on the air-side the porosity occurs on two length-scales, submicrometer as on the opposite size and micrometer where crystals are removed. The importance of surface morphology in the formation of the microstructure is outlined. The role of diffusion and nucleation in the mechanism of surface gold enrichment is established.

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Section: Resultsmentioning

confidence: 67%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 88%

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Dealloying of an Au-based amorphous alloy

2010

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“…Melt spun ribbons display diverse microstructures from the amorphous wheel side to the air side where quenched-in crystals are found. These belong to a metastable cubic phase, Cu 15 Si 4 type which was identified in XRD patterns by comparison with other rapidly quenched ribbons of Au 37.5 Cu 37.5 Si 25 composition [23,24]. These crystals are quickly removed by electrochemical etching as shown by the disappearance of their reflections from the diffraction pattern leaving an incipient porosity of micrometer size on the ribbon surface.…”

Section: Au Based Amorphous Alloymentioning

confidence: 96%

De-alloying of rapidly solidified amorphous and crystalline alloys

Battezzati

Scaglione

2011

Journal of Alloys and Compounds

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De-alloying occurs when a less noble metal is selectively removed from an alloy either by chemical or electrochemical means. Under appropriate experimental conditions and for suitable alloy composition, the resulting material is constituted by crystalline ligaments rich in the noble element and pores. The literature reports a substantial amount of information on de-alloying crystalline homogeneous solid solutions, mostly based on noble metals, whereas the process has been attempted in a limited number of cases with amorphous alloys. The latter case is reviewed here and new results are given for a Au-based metallic glass evidencing the role of the critical potential and surface roughness.It can be also of interest to remove selectively from the alloy a single phase leaving a sieve-like matrix. which might itself be porous. The size of the pores and of the remaining solid can be tailored by controlling the grain size of the phases. Examples are given for this second process and experiments are reported on successful selective etching of rapidly solidified Fe-C eutectics.

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“…[2] Its glass transition is observed at 396 K. [3] Above this temperature, the supercooled liquid remains stable for 57 K at a heating rate of 20 K/min 3 ; therefore, it is envisaged to employ such a material by forming it above glass transition temperature, i.e. exploiting the near-net shape property of the glassy metals.…”

Section: Introductionmentioning

confidence: 99%

XPS study of gold‐based metallic glass

Kačiulis

Mezzi

Fiore

et al. 2010

Surface & Interface Analysis

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New multinary amorphous materials, based on gold, that can be produced in bulk form due to their high glass-forming tendency, were discovered recently. However little is known about their corrosion properties.In the present study, the characterization of Au 49 Cu 26.9 Ag 5.5 Pd 2.3 Si 16.3 amorphous ribbons produced by melt spinning is reported. Their corrosion properties were tested by incubating the samples in artificial sweat and by monitoring the changes in surface structure by SEM and XRD. Before incubation, the surface of the samples was amorphous and flat, characterized only by microfeatures due to the liquid contact with the wheel during quenching. After treatment with artificial sweat, the formation of nanosized crystallites of Au on the sample surface was observed.The surface chemical composition of both sides of the ribbon samples was investigated by XPS. Atomic concentration and chemical states of constituent elements before and after the incubation in artificial sweat were determined. The depth profiling of both sides of the samples was carried out by using Ar ion sputtering combined with cyclic XPS measurements. The segregation of Si on one side of the samples and the changes of chemical composition, caused by the treatment in artificial sweat, were revealed.

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Effect of minor elements addition on glass formation and properties of gold alloys

Cited by 6 publications

References 9 publications

Dealloying of an Au-based amorphous alloy

Dealloying of an Au-based amorphous alloy

De-alloying of rapidly solidified amorphous and crystalline alloys

XPS study of gold‐based metallic glass

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