Thermodynamic Solidification Path Assessment and Microstructural Comparison of Deep Eutectic Au-Cu-Si System

Abstract:

Particularly in karat gold alloys in jewelry applications, many alloy formulations include a small amount of silicon for filigree castings and brightening effect [1]. On the other hand, some alloy manufacturers stayed away from silicon or set a maximum amount of silicon to avoid embrittlement [1-3]. However recent development of gold-based bulk metallic glass involved a large addition of silicon (16.3 at% Si) in the alloy formulation [4-6]. No silicon segregation had been observed in large ingots that were cooled at 100 K/s and above. In the current study of Au55Cu25Si20 alloy, extra silicon has been added to investigate the segregation effect using three different techniques for cross references: equilibrium solidification path, Scheil-Gulliver solidification with ThermoCalc® and microstructural study with varying cooling rates. The amounts of solidified primary and eutectic silicon were measured in three differently cooled ingots. Image analysis using ImageJ® was used to obtain size distributions, area fractions, and volume fractions of silicon in both primary silicon and eutectic silicon.

• Periodical: Applied Mechanics and Materials (Volumes 548-549)
• Pages: 259-263
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.548-549.259
• Online since: April 2014
• Authors: Kamolchanok Thipayarat*, A. Lewan, E. Nisaratanaporn, B. Lohwongwatana
• Keywords: Deep Eutectic, Silicon Segregation, Solidification

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