Alloy MP159® Cobalt Bar - AMS 5842

Alloy 159® is an ultra‑high‑strength nickel‑cobalt multiphase alloy capable of achieving more than 265 ksi (1,830 MPa) tensile strength while still maintaining good ductility, toughness, and corrosion resistance. It is produced using vacuum induction melting (VIM) followed by vacuum arc remelting (VAR) to ensure purity and consistent microstructure. This alloy performs reliably up to about 1100–1200 °F and is used in aerospace, medical, energy, and marine environments.

Because of its strength and toughness, Alloy 159® responds best to high-energy cutting methods such as laser cutting and waterjet cutting. Conventional shearing is generally not recommended except for very thin gauges.

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Characteristics of Alloy 159®

Alloy 159® is designed to reach exceptionally high tensile and yield strengths, especially after age-hardening. It maintains this strength across a wide temperature range, making it ideal for high-load and high-stress environments. Its chemical makeup, which includes high amounts of cobalt, nickel, chromium, and molybdenum, give it excellent solid-solution strengthening, high stability under thermal cycling, and strong resistance to microstructural degradation. Alloy 159® retains strength and toughness at temperatures where many nickel alloys begin to soften. It also offers excellent oxidation resistance, strong creep resistance, and stability during long-term exposure to elevated temperatures. This alloy's microstructure gives it exceptional fatigue life and resistance to stress corrosion cracking. Unlike many ultra‑high‑strength alloys, Alloy 159® maintains usable ductility and toughness, even when fully hardened. This is a major reason it’s trusted in mission‑critical aerospace hardware.

Working with Alloy 159®

Alloy 159® can be formed, but only with care. It has very high strength even before aging, and it work-hardens aggressively. Expect limited cold formability, high forming loads, and risk of cracking if bends are too tight. For best results, form before age-hardening. Heat treatment for this alloy typically starts with solution annealing which improves ductility for forming or machining. Them, age-hardening dramatically increases tensile and fatigue strength. The alloy responds strongly to precipitation hardening, which is why it’s widely used for aerospace fasteners and high‑performance springs. Machining Alloy 159® is challenging, at this alloy was designed to resist deformation. Welding can also prove to be challenging but is possible. If welding is necessary, make sure to use low heat input processing, preheat and control cooling, and weld only when design allows for reduced strength in the joint area.

Other industry standards we comply with:

GE Aircraft Engine (GT193)
GE Aviation S-SPEC-35 AeDMS S-400
RR SABRe Edition 2
PWA LCS
DFARS Compliant

Common Trade Names

MP159® (SPS Technologies)

Industry Applications for Alloy 159®

Landing gears and bolt material
Solid rocket boosters
Jet engines
Chemical processing
Pulp and paper
Power generation equipment
Marine equipment

Chemical Composition

Chemical Composition Percentage of MP159®
	Element	Min	Max
Co	Cobalt	-	36.00
Ni	Nickel	-	25.00
Cr	Chromium	-	19.00
Fe	Iron	-	9.0
Mo	Molybdenum	-	7.00
Ti	Titanium	-	3.00
Nb	Columbium	-	0.60
Al	Aluminum	-	0.20

Physical Properties

Property	Value
Density	0.304 lb/in³

Mechanical Properties

Property	Value
Condition	Annealed
Tensile Strength	843 MPa
Yield Strength	298 MPa
Elongation	60%
Reduction of Area	69%

Datasheet

Download our Alloy 159® datasheet

Additional Info

A Brief History of Alloy 159®

Alloy 159® emerged during the aerospace materials boom of the late 20th century, when engineers needed metals that could withstand extreme mechanical loads, high temperatures, and aggressive environments without sacrificing toughness. Traditional nickel‑based superalloys offered strength or heat resistance, but not both at the ultra‑high levels demanded by next‑generation aircraft and turbine systems.

Cobalt‑based alloys—already known for their thermal stability—became the foundation for a new class of ultra‑high‑strength materials. Alloy 159® was one of the standout results: a cobalt‑nickel‑chromium‑molybdenum alloy engineered to deliver exceptional strength, fatigue resistance, and oxidation stability across a wide temperature range.

How Alloy 159® Was Developed

Alloy 159® was developed through a combination of advanced alloy design and precipitation‑hardening metallurgy. Engineers sought an alloy that could:

Achieve extremely high tensile and yield strength
Maintain toughness even when fully hardened
Resist oxidation and creep at elevated temperatures
Withstand severe cyclic loading

To achieve this, metallurgists blended cobalt with nickel, chromium, and molybdenum, then optimized the alloy for solution annealing and age‑hardening. The result was a material capable of reaching strength levels far beyond conventional stainless steels or nickel alloys, while still offering the ductility needed for aerospace fasteners and high‑performance springs.

Early Applications of Alloy 159®

When Alloy 159® was introduced, it quickly found a home in industries where failure was not an option. Early adopters included aerospace manufacturers, gas-turbine designers, defense and propulsion systems, and high-performance mechanical assemblies.

How Alloy 159® is Used Today

Today, Alloy 159® remains a premium choice for mission‑critical components that demand extreme mechanical performance. Its modern applications span aerospace, energy, medical, and high‑performance engineering sectors.

Aerospace & Defense: Fasteners, actuation hardware, springs, hot-section turbine parts
Power Generation: Combustion-zone components, high-temperature hardware
Medical: Surgical and orthopedic components, springs

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Product FAQs

Cobalt 159 offers high tensile strength, fatigue resistance, and toughness, making this alloy best for high-stress environments such as jet engines, medical implants, and energy systems.

This alloy is slightly magnetic, which is typical of cobalt-based superalloys, especially after age-hardening.