Low-alloyed gold

FIGURE 7.4 Hardness trends in as-cast 22kt An depending on base metal additions [21]. (From Hardening of low-alloyed gold, J. Fischer-BUhner, Gold Bulletin, 2005, 38(3), 120-131. With permission.)... 

Doped and low-alloyed gold bonding wires, Ch. Simons, L. Schrapler, and G. Herklotz, Gold Bulletin, 2000, 33(3), 89. 

Hardening of low-alloyed gold, J. Fischer-Biihner, Gold Bulletin, 2005,38(3), 120-131. 

GoldJilloys, Wrought Type. Two types of wrought gold alloys were formerly recognized by the ADA specification no. 7 for the fabrication of orthodontic and prosthetic dental appHances, ie, type I, high-precious-metal alloys, and type II, low-precious-metal alloys (gold color). Alloys of this type are seldom used in the United States they have been replaced by stainless steels and nickel—titanium alloys. 

The stress corrosion cracking of low carat gold alloys during manufacture and storage is a perennial problem and has been reviewed by Dugmore and DesForges". ... 

Platinum is especially suitable for this application because even at high temperatures it has a good stability and a good resistance to contamination. However, different metals, all having a positive temperature coefficient, may be used, such as tungsten (for very high-temperature applications), nickel and nickel alloys and also (but rarely because of their low resistivity) gold and silver. 

Platinum, gold, graphite and silver are not compatible with low-alloy steel, aluminum, magnesium, copper, and cadmium - other combinations are compatible... 

Alkaline cyanide baths may be used to obtain either matt or bright deposits. Gold deposits from alkaline cyanide baths in the absence of brighteners or grain refiners have a columnar structure and a matt appearance. Gold from alkaline cyanide baths is usually brightened by addition of metals such as Sn, Sb, and Ag. Low alloyed Ag deposits (Ag content less than 1%) are particularly attractive for the ease of operation and control of the baths and because of room temperature operation. 

The solder and ahoy market, including low melting or fusible ahoys, is a principal user of indium (see SoLDERS AND BRAZING ALLOYS). The addition of indium results in unique properties of solders such as improved corrosion and fatigue resistance, increased hardness, and compatibhity with gold substrates. To fachitate use in various appHcations, indium and its ahoys can be easily fabricated into wine, ribbon, foil, spheres, preforms, solder paste, and powder. 

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