Superalloys based on nickel for the production of articles are having a tolerance improved at the grain boundaries has low disorientation

摘要

Nickel-base superalloys are provided which produce single crystal articles having improved tolerance to low angle grain boundaries and an improved balance between cyclic oxidation and hot corrosion resistance. The improved tolerance arises from the discovery that nickel-base superalloys suitable for casting as single crystal articles can be improved by the addition of small, but controlled, amounts of boron and carbon, and optionally hafnium, and is manifested principally by improved grain boundary strength. As one result of this increased grain boundary strength, grain boundary mismatches far greater than the 6 DEG limit for prior art single crystal superalloys can be tolerated in single crystal articles made from the nickel-base superalloys of this invention. These alloys are especially useful when directionally solidified as hot-section components of aircraft gas turbine engines, particularly rotating blades and stationary vanes.