TREATMENT OF BORON-CONTAINING, PLATINUM GROUP METAL-BASED ALLOYS
Castings made of boron-containing alloys based on at least one platinum group metal are treated by thermal ageing in the presence of oxygen and at temperatures below the melting point of the alloy. This enables the alloys to be processed at temperatures customary in the jewelry industry. The treated castings can also be processed into medical technology products.
1 .- 10 . (canceled)
11 . A method for treatment of castings made of a boron-containing alloy based on at least one platinum group metal and containing 1-3% by weight of boron, the method comprising carrying out a plurality of thermal ageing procedures in a presence of oxygen and at temperatures below a melting point of the alloy, and after each of the thermal ageing procedures treating a surface of the alloy with water to remove boric oxide generated on a surface of the alloy during the thermal ageing procedure.
12 . The method according to claim 11 , wherein toughness of the casting is checked after each treatment.
13 . The method according to claim 11 , wherein the alloy to be treated contains 1.5 to 2.5% by weight of boron.
14 . The method according to claim 11 , wherein the alloy to be treated is selected from the group consisting of boron with a platinum group metal, and boron with an alloy selected from the group consisting of Pt96Cu4; Pt95.2Ru4.8; Pt95W5; Pt80Ir20; Pt90Ir10; Pt95Co5; Pd95.2Ru4.8; and Pd95(InGa)5.
15 . A casting made from a boron-containing alloy based on at least one platinum group metal, wherein the casting was treated according to the method of claim 11 .
16 . The casting according to claim 15 , having a Vickers hardness which decreases from a core to an external surface of the casting.
17 . The casting according to claim 16 , wherein the Vickers hardness decreases by more than 50% from the core to the external surface of the casting.
18 . The casting according to claim 15 , wherein the casting has a microstructure in which a number of metallic phases decreases from a core to an external surface of the casting.