An improved sterling silver alloy. Like all sterlings, the improved alloy is at least 92.5 percent silver by weight. It has less copper than traditional sterlings: 3.0 percent versus the traditional 7.5 percent. Additionally, the improved alloy includes about 2.75 percent palladium, about 1.0 percent tin, and about 0.75 percent zinc, all by weight. A grain refiner, such as ruthenium, may also be provided. The components of the preferred alloy are melted, degassed, remelted, and then formed into casting grains, wire, and etc. The resulting alloy is significantly harder, as cast, than traditional sterlings: 95-120 Vickers versus 65 Vickers for traditional sterlings. The improved alloy also exhibits improved corrosion resistance. Other than a slightly higher (<200 F.) liquidus temperature, the improved alloy may be worked in substantially the same manner as traditional sterlings. Pieces cast from the improved alloy may be age hardened to about 160 Vickers, if desired.

An improved sterling silver alloy. Like all sterlings, the improved alloy is at least 92.5 percent silver by weight. It has less copper than traditional sterlings: 3.0 percent versus the traditional 7.5 percent. Additionally, the improved alloy includes about 2.75 percent palladium, about 1.0 percent tin, and about 0.75 percent zinc, all by weight. A grain refiner, such as ruthenium, may also be provided. The components of the preferred alloy are melted, degassed, remelted, and then formed into casting grains, wire, and etc. The resulting alloy is significantly harder, as cast, than traditional sterlings: 95-120 Vickers versus 65 Vickers for traditional sterlings. The improved alloy also exhibits improved corrosion resistance. Other than a slightly higher (<200 F.) liquidus temperature, the improved alloy may be worked in substantially the same manner as traditional sterlings. Pieces cast from the improved alloy may be age hardened to about 160 Vickers, if desired.

The present invention provides an artifactless superelastic alloy including a AuCuAl alloy, the superelastic alloy containing Cu in an amount of 20 atom % or more and 40 atom % or less, Al in an amount of 15 atom % or more and 25 atom % or less, and Au as a balance, the superelastic alloy having a bulk magnetic susceptibility of 24 ppm or more and 6 ppm or less. The Ni-free superelastic alloy of the present invention is capable of exhibiting superelasticity in a normal temperature range, and hardly generated artifacts in a magnetic field environment. The alloy can be produced by setting a casting time in a melting and casting step to a fixed time, and hot-pressing an alloy after casting to make material structures homogeneous.

The present invention provides an artifactless superelastic alloy including a AuCuAl alloy, the superelastic alloy containing Cu in an amount of 20 atom % or more and 40 atom % or less, Al in an amount of 15 atom % or more and 25 atom % or less, and Au as a balance, the superelastic alloy having a bulk magnetic susceptibility of 24 ppm or more and 6 ppm or less. The Ni-free superelastic alloy of the present invention is capable of exhibiting superelasticity in a normal temperature range, and hardly generated artifacts in a magnetic field environment. The alloy can be produced by setting a casting time in a melting and casting step to a fixed time, and hot-pressing an alloy after casting to make material structures homogeneous.

Alloy for the manufacturing of jewels or clock components with minimum concentrations of gold of 75 wt %, of copper between 5% and 21%, of silver between 0% and 21%, of iron between 0.5% and 4% and vanadium between 0.1% and 2.0%, intended to increase the tarnishing-resistance of alloys with a minimum content of gold of 75 wt % under environments in which Sulphur- and chlorine-compounds are present.

Alloy for the manufacturing of jewels or clock components with minimum concentrations of gold of 75 wt %, of copper between 5% and 21%, of silver between 0% and 21%, of iron between 0.5% and 4% and vanadium between 0.1% and 2.0%, intended to increase the tarnishing-resistance of alloys with a minimum content of gold of 75 wt % under environments in which Sulphur- and chlorine-compounds are present.

The present invention relates to a method for producing a platinum-based alloy powder, the method comprising a heat treatment of a mixed powder containing a platinum-based powder composed of at least one selected from the group consisting of platinum and platinum compound, a platinum group metal-based powder composed of at least one selected from the group consisting of iridium, rhodium, palladium, and compound containing at least one of them, and an alkaline-earth metal compound, wherein specific surface area of the platinum group metal-based powder is 30 m.sup.2/g or more and D90 of the mixed powder is 1.0 m or less. According to the method for producing a platinum-based alloy powder of the invention, it is possible to produce a platinum-based alloy powder that has a desired particle diameter, also has a sharp particle size distribution, and has high purity and crystallinity.

The present invention relates to a method for producing a platinum-based alloy powder, the method comprising a heat treatment of a mixed powder containing a platinum-based powder composed of at least one selected from the group consisting of platinum and platinum compound, a platinum group metal-based powder composed of at least one selected from the group consisting of iridium, rhodium, palladium, and compound containing at least one of them, and an alkaline-earth metal compound, wherein specific surface area of the platinum group metal-based powder is 30 m.sup.2/g or more and D90 of the mixed powder is 1.0 m or less. According to the method for producing a platinum-based alloy powder of the invention, it is possible to produce a platinum-based alloy powder that has a desired particle diameter, also has a sharp particle size distribution, and has high purity and crystallinity.

Metal alloys including platinum are disclosed. The alloys have a similar variety of applications to platinum-based alloys. The alloy with a solid solution matrix consisting of: Platinum (Pt) 20 to 70 at. %; Palladium (Pd)>0 to 70 at. %; Cobalt (Co)>0 to 50 at. % and at least one of: Nickel (Ni) up to 50 at. %; Chromium (Cr) up to 50 at. % and Iron up to 50 at. %.

Metal alloys including platinum are disclosed. The alloys have a similar variety of applications to platinum-based alloys. The alloy with a solid solution matrix consisting of: Platinum (Pt) 20 to 70 at. %; Palladium (Pd)>0 to 70 at. %; Cobalt (Co)>0 to 50 at. % and at least one of: Nickel (Ni) up to 50 at. %; Chromium (Cr) up to 50 at. % and Iron up to 50 at. %.