Development of novel 18-karat, premium-white gold bulk metallic glasses with improved tarnishing resistance

Gross, Oliver; Eisenbart, Miriam; Schmitt, Lothar M.; Neuber, Nico; Ciftci, Lamia; Klotz, Ulrich; Busch, Ralf; Gallino, Isabella

doi:10.1016/j.matdes.2017.12.007

Cited by 11 publications

(9 citation statements)

References 28 publications

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“…Plate-shaped amorphous specimens are prepared by tilt casting the melt into a water-cooled copper mold under high-purity argon atmosphere, as described in detail in [11,13,22,39]. The amorphous state is veri ed by x-ray diffraction.…”

Section: Methodsmentioning

confidence: 99%

“…They are found in e.g. Zr- [1][2][3], Fe- [4,5], Ti- [6,7], Mg- [8,9], Au- [10,11], Pt- [12,13], or Pd-based [14,15] systems with usually three or more alloy components. Due to their amorphous structure and the resulting absence of dislocation movement as deformation mechanism, these materials show promising mechanical properties like high strength, hardness, and polymer-like elastic deformability of about 2%, thereby often exceeding the performance of conventional crystalline alloys [16].…”

Section: Introductionmentioning

confidence: 99%

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Determining the fragility of bulk metallic glass forming liquids via modulated DSC

Frey

Neuber

Gross

et al. 2020

J. Phys.: Condens. Matter

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Temperature modulated DSC is used to study the fragility of three different bulk metallic glass forming liquids. Through applying various modulation frequencies, the dynamic glass transition shifts in temperature, allowing to determine the temperature dependence of the average relaxation time for each system. The resulting fragilities are compared with fragility investigations in literature obtained using thermo-mechanical analysis and the heating rate dependence of the calorimetric glass transition. Different methods to compare the data are evaluated and discussed.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Determining the fragility of bulk metallic glass forming liquids via modulated DSC

Frey

Neuber

Gross

et al. 2020

J. Phys.: Condens. Matter

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“…The hottest topics currently in the research are the reduction of precious metal content from deposits (e.g., from 24 kt gold to 18 kt gold) [160,161] while maintaining good corrosion characteristics, mainly acting on the porosity and compactness of deposits, as well as the use of new alloy materials; the replacement of cyanide from many baths with non-toxic compounds [162]; the elimination of heavy metals which are more or less harmful, such as cadmium, nickel, and palladium [106]; new methods of the management and control of waste and waste water, alternative engineering [163][164][165] processes, and the synthesis of new alloys.…”

Section: Discussionmentioning

confidence: 99%

Electroplating for Decorative Applications: Recent Trends in Research and Development

et al. 2018

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Electroplating processes are widely employed in industrial environments for a large variety of metallic coatings, ranging from technological to decorative applications. Even if the galvanic electrodeposition is certainly a mature technology, new concepts, novel applications, environmental legislation and the new material requirements for next-generation devices make the scientific research in this field still very active. This review focuses mostly at the decorative and wearable applications, and aims to create a bridge between the past knowledge and the future direction that this process, i.e., electrodeposition, is taking. Both the theoretical fundamentals as well as some of the most widespread practical applications-limited to metallic and alloy coatings-are explored. As an integral part of the industrial process, we take a look at the main techniques thought which the quality control of deposits and surfaces is carried out. Finally, global industrial performance and research directions towards sustainable solutions are highlighted.

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“…Its initial white color only changes over time to a slight rose color, instead of a non-appealing dark-red, while still possessing the, compared to crystalline 18 K Au alloys, superior mechanical properties (see SI-table I). Therefore it marks an alloy that could nally be used in jewelry applications [6].…”

Section: Introductionmentioning

confidence: 99%

“…This equation is derived from basic heat transfer concepts and makes use of standard values of heat capacity and thermal conductivity for metallic melts. Based on the formula and the experimental d c (5 mm for Au-BMG[24] and 3 mm for the AuGa-BMG[6]) a CCR of 40 K s −1 for the Au-BMG and 111 K s −1 for the AuGa-BMG would be expected. Despite a correct qualitative trend is observed, it appears that the determination of the CCR in the FDSC does not allow a one by one translation to the macroscopic glass forming ability using this established formula with experimental data of the critical thickness.The isothermal time-temperature-transformation diagram of the alloy Au 49 Ag 5.5 Pd 2.3 Cu 26.9 Si 16.3 is depicted in gure 2.…”

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confidence: 99%

Ultrafast scanning calorimetry of newly developed Au-Ga bulk metallic glasses

Neuber

Frey

Gross

et al. 2020

J. Phys.: Condens. Matter

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The isothermal crystallization times and critical cooling rates of the liquid phase are determined for the two bulk metallic glass forming alloys Au 49 Ag 5.5 Pd 2.3 Cu 26.9 Si 16.3 and Au 51.6 Ag 5.8 Pd 2.4 Cu 20.2 Ga 6.7 Si 13.3 by using fast differential scanning calorimetry, covering the whole timescale of the crystallization event of the metallic melt. In the case of Au 49 Ag 5.5 Pd 2.3 Cu 26.9 Si 16.3 , a typical crystallization nose was observed, whereas for the Au 51.6 Ag 5.8 Pd 2.4 Cu 20.2 Ga 6.7 Si 13.3 , a more complex crystallization behavior with two distinct crystallization noses was found. Even for the complex crystallization behavior of the Au 51.6 Ag 5.8 Pd 2.4 Cu 20.2 Ga 6.7 Si 13.3 alloy it is shown that the minimal isothermal nose time τ * x does allow for a quanti cation of the macroscopic critical thickness. It is discussed in contrast to the critical cooling rate, which is found to allow less exact calculations of the critical thickness and thus does not correlate well with the critical cooling rate from macroscopic experiments. Additionally the crystallization data of Au 49 Ag 5.5 Pd 2.3 Cu 26.9 Si 16.3 was modeled using classical nucleation theory with the Johnson-Mehl-Avrami-Kolmogorov (JMAK) equation, enabling a determination of the interfacial energy.

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Development of novel 18-karat, premium-white gold bulk metallic glasses with improved tarnishing resistance

Cited by 11 publications

References 28 publications

Determining the fragility of bulk metallic glass forming liquids via modulated DSC

Determining the fragility of bulk metallic glass forming liquids via modulated DSC

Electroplating for Decorative Applications: Recent Trends in Research and Development

Ultrafast scanning calorimetry of newly developed Au-Ga bulk metallic glasses

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