Abstract: A thermally stable, oxidation-resistant nickel-base alloy having good engineering properties for use in mechanical equipment operated at temperatures of up to 1600.degree. F. or higher is provided by maintaining the nickel content above 50% by weight and including as essential elements from about 12 to about 18% chromium, from about 8 to about 18% molybdenum and from about 0.005 to about 0.2% lanthanum by weight. Additional elements may be included in limited amounts provided that the average N.sub.v number of the alloy as defined herein is not substantially above about 2.5 and preferably is below about 2.4.

Abstract: A nickel-base alloy is provided having excellent corrosion resistance to both oxidizing and reducing environments in all of the annealed, welded and thermally aged conditions. The alloy has the broad composition:______________________________________ Chromium 12-18 Molybdenum 10-18 Iron 0-3 Tungsten 0-7 Aluminum <0.5 Carbon 0.02 max. Silicon 0.08 max. Cobalt <2 Manganese <0.5 One of the group Titanium, up to 0.

Abstract: A cast thermally stable high temperature nickel-base alloy characterized by superior oxidation resistance, sustainable hot strength and retention of ductility on aging is provided by maintaining the alloy chemistry within the composition molybdenum 13.7% to 15.5%; chromium 14.7% to 16.5%; carbon up to 0.1%, lanthanum in an effective amount to provide oxidation resistance up to 0.08%; boron up to 0.015%; manganese 0.3% to 1.0%; silicon 0.2% to 0.8; cobalt up to 2.0%; iron up to 3.0%; tungsten up to 1.0%; copper up to 0.4%; phosphorous up to 0.02%; sulfur up to 0.015%; aluminum 0.1% to 0.5% and the balance nickel while maintaining the Nv number less than 2.31.