Grain-refined recrystallized 14-carat gold alloy

Riabkina, M.; Gal‐Or, L.; Fishman, Yevgeny Krivolapov. Shmuel; Iram, G.

doi:10.1007/bf03214701

Cited by 7 publications

(2 citation statements)

References 7 publications

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“…27 while Au-Ir is suspected to be eutectic but with a very small eutectic composition. 28 Therefore, we will focus in this section on the Al-Zn:Cr system, since the phase diagrams (binaries and ternary) are fairly well known, and for the sake of simplicity we further restrict our discussion to the binary Al-Cr system.…”

Section: Frank Suggested In the 1950smentioning

confidence: 99%

Thermodynamic Aspects of Homogeneous Nucleation Enhanced by Icosahedral Short Range Order in Liquid Fcc-Type Alloys

Rappaz

Kurtuldu

2015

JOM

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We have recently shown that minute solute element additions to liquid metallic alloys can strongly influence the nucleation of the fcc phase and act as a grain refinement method. Electron back-scattered diffraction observations revealed a concomitant increase in the percentage of nearest neighbor (nn) grains that are in a twin relationship. Furthermore, multiple-twinned (MT) nn grain configurations with a fivefold symmetry around a common h110i direction have been identified, an occurrence that can be explained when the symmetry of the icosahedron is accounted for. It was then conjectured that a new nucleation mechanism occurs in two steps: first, the formation of small icosahedral quasicrystals in the melt, followed by heteroepitaxy of the fcc phase on facets of these quasicrystals. In the present contribution, based on thermodynamics arguments, it is proposed that the first step occurs by spinodal decomposition of the liquid, in a manner similar to Guinier-Preston zones formation in solid state precipitation, while the second step is a transformation of these quasicrystal precursors into MT-fcc nanocrystals once the driving force for this transformation is sufficient to overcome the fcc-liquid interfacial energy and the elastic strains associated with MT-fcc nanoparticles. This explanation sets up guidelines for finding solute elements and composition ranges that favor this grain refinement mechanism.

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Section: Frank Suggested In the 1950smentioning

confidence: 99%

Thermodynamic Aspects of Homogeneous Nucleation Enhanced by Icosahedral Short Range Order in Liquid Fcc-Type Alloys

Rappaz

Kurtuldu

2015

JOM

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“…Boron is known to be a grain refiner and hardener in 18 carat alloys [12], even if the solubility levels of this element are about a mass fraction of 3‰ in gold and nearly zero in platinum [13]. The hardening effect begins at a mass fraction of 0.8‰ in gold alloy.…”

Section: Px Group Alloysmentioning

confidence: 99%

Metallurgical characterization of materials for the reference mass standard of the French watt balance experiment

Meury¹,

Molins²,

Genevès³

2010

Metrologia

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Watt balance experiments are intended to link the mass unit to the Planck constant. Therefore, in these experiments, a reference mass standard is necessary. However, in the French apparatus, the platinum-iridium alloy that forms the international prototype of the kilogram cannot be considered because of its magnetic susceptibility. Consequently, new materials were investigated, according to stringent specifications. This led to the selection of alloys based on precious metals. The stability of the materials used in mass metrology is strongly dependent on bulk homogeneity and cleanliness: after the investigation of different production modes and heating treatments, microstructural and analytical studies were performed. The critical properties of the different materials were examined and discussed in comparison with the platinum-iridium alloy.

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Noble Metals and Their Alloys

Schlamp¹

2006

Materials Science and Technology

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Grain-refined recrystallized 14-carat gold alloy

Cited by 7 publications

References 7 publications

Thermodynamic Aspects of Homogeneous Nucleation Enhanced by Icosahedral Short Range Order in Liquid Fcc-Type Alloys

Thermodynamic Aspects of Homogeneous Nucleation Enhanced by Icosahedral Short Range Order in Liquid Fcc-Type Alloys

Metallurgical characterization of materials for the reference mass standard of the French watt balance experiment

Noble Metals and Their Alloys

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