In modern society gold is mainly used in the banking, jewelry and technology sectors. Among them, more than half of the gold will be used in the jewelry industry. It is well known that fine gold has a low Vickers hardness and yield strength, which limit its application in the electronics, semiconductor and jewelry industries. How to strengthen fine gold and keep its high purity at the same time have important theoretical and practical significance, especially in lowering the cost of gold jewelry pieces.

Among the many ways to strengthen fine gold, the addition of trace elements (no more than 1 wt.%) is the easiest. This paper will report on an extensive research project designed to determine which elements are the most effective in strengthening fine gold. This research resulted in finding a trace element alloy that improved the hardness of fine gold from 31 to 220 Vickers hardness and at the same time caused the color to change. Using this new, hard micro-alloyed gold as a thin protective coating applied by physical vapor deposition (sputtering) will also be discussed. The results of this research can be a valuable reference for other metallurgists working on micro-alloyed fine gold compositions.

Author: Dr. Juzi Li