several distinct groups; the alloys in the same group have similar properties and uses. Pure metals Unalloyed. Often noble metals – silver, gold, palladium. Ag-Cu Silver-copper. Good melting properties. Silver enhances flow. Eutectic alloy used for furnace brazing. Copper-rich alloys prone to stress cracking by ammonia. Ag-Zn Silver-zinc. Similar to Cu-Zn, used in jewelry due to its high silver content so that the product is compliant with hallmarking. The color matches silver, and it is resistant to ammonia-containing silver-cleaning fluids. Cu-Zn (brass) Copper-zinc. General purpose, used for joining steel and cast iron. Corrosion resistance usually inadequate for copper, silicon bronze, copper-nickel, and stainless steel. Reasonably ductile. High vapor pressure due to volatile zinc, unsuitable for furnace brazing. Copper-rich alloys prone to stress cracking by ammonia. Ag-Cu-Zn Silver-copper-zinc. Lower melting point than Ag-Cu for same Ag content. Combines advantages of Ag-Cu and Cu-Zn. At above 40% Zn the ductility and strength drop, so only lower-zinc alloys of this type are used. At above 25% zinc less ductile copper-zinc and silver-zinc phases appear. Copper content above 60% yields reduced strength and melts above 900 °C. Silver content above 85% yields reduced strength, high liquidus and high cost. Copper-rich alloys prone to stress cracking by ammonia. Silver-rich brazes (above 67.5% Ag) are hallmarkable and used in jewellery; alloys with lower silver content are used for engineering purposes. Alloys with copper-zinc ratio of about 60:40 contain the same phases as brass and match its color; they are used for joining brass. Small amount of nickel improves strength and corrosion resistance and promotes wetting of carbides. Addition of manganese together with nickel increases fracture toughness. Addition of cadmium yields Ag-Cu-Zn-Cd alloys with improved fluidity and wetting and lower melting point; however cadmium is toxic. Addition of tin can play mostly the same role. Cu-P Copper-phosphorus. Widely used for copper and copper alloys. Does not require flux for copper. Can be also used with silver, tungsten, and molybdenum. Copper-rich alloys prone to stress cracking by ammonia. Ag-Cu-P Like Cu-P, with improved flow. Better for larger gaps. More ductile, better electrical conductivity. Copper-rich alloys prone to stress cracking by ammonia. Au-Ag Gold-silver. Noble metals. Used in jewelry. Au-Cu Gold-copper. Continuous series of solid solutions. Readily wet many metals, including refractory ones. Narrow melting ranges, good fluidity. Frequently used in jewellery. Alloys with 40–90% of gold harden on cooling but stay ductile. Nickel improves ductility. Silver lowers melting