René 100 is a cast nickel-base superalloy developed by General Electric as a very-high-strength turbine blade material, sharing the same base chemistry family as IN100 (both are members of the same 1960s-era Ni-Cr-Co-Mo-Al-Ti "100-series" alloy lineage developed for higher operating temperatures than the first-generation wrought superalloys). It is standardized under Werkstoff Nr. 2.4674, DIN designation NiCo15Cr10MoAlTi — a name that itself spells out the core recipe: nickel base, ~15% cobalt, ~10% chromium, plus molybdenum, aluminum, and titanium.

The alloy relies on an unusually high combined aluminum + titanium content (about 9.7% between the two) to drive a very high volume fraction of the strengthening gamma-prime phase, which is what gives René 100 its exceptional high-temperature strength relative to earlier cast superalloys — at the cost of being one of the more difficult grades in this family to cast without micro-porosity or freckle defects, and correspondingly demanding to machine.

Typical applications are precision-investment-cast turbine blades and other rotating hot-section components in jet engines and industrial gas turbines, where sustained strength at temperature outweighs the cost and processing difficulty of the alloy.

René 100 sits at the difficult end of the cast nickel-superalloy spectrum. Its high combined Al+Ti content produces a dense gamma-prime volume fraction that keeps the alloy hard and strong well past the temperatures where steel would soften, so cutting forces and edge temperatures both stay elevated throughout a cut rather than easing off at higher speeds. Low thermal conductivity concentrates that heat at the tool-chip interface instead of carrying it away in the chip, accelerating crater wear on tooling not suited to superalloys.

Work hardening is aggressive: any hesitation, rubbing, or light interrupted cut immediately hardens the surface layer, so consistent, adequate chip load with no dwelling is essential. As a cast structure, René 100 also carries carbide and topologically-close-packed phase particles distributed through the grain structure that behave abrasively against the cutting edge — a factor separate from, and in addition to, the alloy's inherent hot strength.

Nickel's affinity for common tool materials promotes galling and built-up edge, which tears the finished surface if the edge is not kept sharp. Rigid, low-deflection setups, sharp positive-rake carbide with a fine, uniform edge hone, and continuous, well-directed coolant are the standard countermeasures for this grade.