MAR-M509 Cobalt-base Superalloy

Mar M509 is among the most widely deployed and thoroughly characterized cast cobalt-base superalloys for turbine applications, particularly suited to turbine vanes requiring a balanced combination of high-temperature strength, thermal fatigue resistance and superior oxidation resistance.

Cobalt constitutes the balance of the alloy at approximately 55 wt%, while chromium (21.5–23.5 wt%) delivers primary protection against oxidation and hot corrosion. Its designation CoCr24Ni10WTaZrB reflects a nickel addition (~10 wt%) for enhanced ductility. Additional alloying elements including tungsten, tantalum, zirconium and boron work collectively to achieve strengthening via carbide and boride precipitates.

Tantalum (~3.5 wt%) reacts with carbon (~0.6 wt%) to form MC-type carbides dispersed throughout the cast microstructure. Boron (~0.1 wt%) and zirconium (~0.5 wt%) improve grain boundary strength and hot-cracking resistance. Extensive academic studies have been conducted on the structural stability of MARM 509. Accordingly, its machinability is well established among manufacturing shops routinely machining cast cobalt superalloys.

Mar-M509 is a high-strength, cobalt-based cast superalloy designed for extreme high-temperature environments up to 1050 °C.

Tungsten,W 6.50-7.50%

Chromium, Cr 23.0-24.25%

Tantalum,Ta 3.00-4.00%

Phosphorus,P ≤0.015%

Carbon,C 0.55-0.65%

Zirconium,Zr 0.30-0.50%

Titanium, Ti 0.15-0.25%

Boron,B 0.005-0.010%

Manganese,Mn ≤0.10%

Sulfur,S ≤0.01%

Silicon,Si, ≤0.30%

Iron,Fe ≤1.00%

Nickel,Ni ≤9.0-11.0%

Cobalt, Co Balance

• Material Type:  Cobalt-based precipitation-hardening equiaxed cast superalloy (CoNiCrWTa group).
• Density: ~8.85 g/cm³.
• Maximum Service Temperature: Up to 1050 °C to 1100 °C.
• Main Strengthening Phase: Carbides dispersed along grain boundaries and dendritic structures.
• Corrosion & Oxidation Resistance: Good oxidation resistance up to roughly 1038 °C (1900 °F) and strong hot-corrosion resistance at 871 °C (1600 °F).

• High-Temperature Strength: Retains structural integrity and resists deformation at service temperatures up to 1050°C (1900°F).
• Creep Resistance: Features a unique carbide structure that prevents permanent stretching or sagging under heavy loads over time.
• Corrosion Resistance: Offers excellent resistance to hot-corrosion, oxidation, and sulfidation compared to many nickel-based alternatives.
• Thermal Shock Resistance: Withstands rapid shifts between extreme heat and cool temperatures without cracking.