Patent ID: 6986381

Claim:
A method of making cast shapes of a metallic alloy, comprising the steps of: melting the alloy to form a melt under vacuum or partial pressure of inert gas; pouring the melt of the alloy into a cavity of a composite mold comprising a substrate of isotropic graphite having a mold cavity, wherein the surface of the mold cavity is coated with a coating of a refractory metal such as W or Re or a refractory metal carbide such as TaC or HfC having a thickness from 2 to 500 microns, and wherein the graphite of the substrate of the mold has isotropic grains with grain size between 3 and 10 microns, flexural strength between about 7,000 and 20,000 psi, compressive strength between about 12,000 and 35,000 psi, and porosity below about 13%; and solidifying the melted alloy into a body taking the shape of the mold cavity.