Abstract: An alloy having the following composition limits by weight:Chromium 13-15%, silicon 3.4-4.2%, boron 1.7-2.3% and the balance nickel, is cast in a mold that is made by the lost wax process from CaCO.sub.3, so that when the molten metal alloy is cast in the preheated mold at 2300.degree. F., held in a furnace at 1750.degree. F. for an hour, and then rapidly cooled to room temperature. The casting will have a fairly low hardness of R.sub.c 30.+-.3 so that it can be machined. After machining, the casting is heated to a temperature of 1150.degree. F. for at least three hours before cooling, resulting in a casting that is hardened to R.sub.c 45 to R.sub.c 50.