Alacrite (also known as Alloy L-605, Cobalt L-605, Haynes 25, and occasionally F90) is a family of

cobalt Cobalt is a chemical element with the symbol Co and atomic number 27. As with nickel, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, pr ...

-based

alloy An alloy is a mixture of chemical elements of which at least one is a metal. Unlike chemical compounds with metallic bases, an alloy will retain all the properties of a metal in the resulting material, such as electrical conductivity, ductility, ...

s. The alloy exhibits useful mechanical properties and is oxidation- and

sulfidation Sulfidation (British spelling also sulphidation) is a process of installing sulfide ions in a material or molecule. The process is widely used to convert oxides to sulfides but is also related to corrosion and surface modification. Inorganic, mate ...

-resistant. One member of the family, XSH Alacrite, is described as "a non-magnetic, stainless super-alloy whose high surface hardness enables one to achieve a mirror quality polish." The Institut National de Métrologie in

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...

has also used the material as a

kilogram The kilogram (also kilogramme) is the unit of mass in the International System of Units (SI), having the unit symbol kg. It is a widely used measure in science, engineering and commerce worldwide, and is often simply called a kilo colloquially ...

mass standard.

Composition and standardization

L-605 is composed primarily of

(Co), with a specified mixture of

chromium Chromium is a chemical element with the symbol Cr and atomic number 24. It is the first element in group 6. It is a steely-grey, lustrous, hard, and brittle transition metal. Chromium metal is valued for its high corrosion resistance and hardne ...

(Cr),

tungsten Tungsten, or wolfram, is a chemical element with the symbol W and atomic number 74. Tungsten is a rare metal found naturally on Earth almost exclusively as compounds with other elements. It was identified as a new element in 1781 and first isolat ...

(W),

nickel Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive but large pieces are slow to ...

(Ni),

iron Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in f ...

(Fe) and

carbon Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent In chemistry, the valence (US spelling) or valency (British spelling) of an element is the measure of its combining capacity with o ...

(C), as well as small amounts of

manganese Manganese is a chemical element with the symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese is a transition metal with a multifaceted array of industrial alloy use ...

(Mn),

silicon Silicon is a chemical element with the symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic luster, and is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic tab ...

(Si), and

phosphorus Phosphorus is a chemical element with the symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Ear ...

(P). The tungsten and nickel improve the alloy's machinability, while chromium contributes to its solid-solution strengthening. The following tolerances must be met to be considered an L-605 alloy:

Properties and Applications

Alacrite or Alloy L-605 is one of the strongest cobalt alloys available. It is highly resistant to scaling and oxidation, and can be used in oxidising environments up to temperatures of 1093°C. Alloy L605 can be welded using gas tungsten arc, gas metal arc, shielded metal arc, electron beam and resistance welding. It’s important to use good joint fit-up, minimum restraint, low interpass temperature and cool rapidly when welding. For maximum ductility, fabricated components should be annealed 1176-1232°C and rapidly cooled. The alloy was originally developed for application in aircraft, including combustion chambers, liners, afterburners and the hot section of gas turbines. It has also been used in

aerospace Aerospace is a term used to collectively refer to the atmosphere and outer space. Aerospace activity is very diverse, with a multitude of commercial, industrial and military applications. Aerospace engineering consists of aeronautics and astrona ...

components and

turbine engines A turbine ( or ) (from the Greek , ''tyrbē'', or Latin ''turbo'', meaning vortex) is a rotary mechanical device that extracts energy from a fluid flow and converts it into useful work. The work produced by a turbine can be used for generating e ...

as well as drug-eluting and other kinds of

stent In medicine, a stent is a metal or plastic tube inserted into the lumen of an anatomic vessel or duct to keep the passageway open, and stenting is the placement of a stent. A wide variety of stents are used for different purposes, from expandab ...

s due to its

biocompatibility Biocompatibility is related to the behavior of biomaterials in various contexts. The term refers to the ability of a material to perform with an appropriate host response in a specific situation. The ambiguity of the term reflects the ongoing de ...

. When used for implantable

medical device A medical device is any device intended to be used for medical purposes. Significant potential for hazards are inherent when using a device for medical purposes and thus medical devices must be proved safe and effective with reasonable assura ...

s, the

ASTM ASTM International, formerly known as American Society for Testing and Materials, is an international standards organization that develops and publishes voluntary consensus technical standards for a wide range of materials, products, systems, an ...

F90-09 and

ISO ISO is the most common abbreviation for the International Organization for Standardization. ISO or Iso may also refer to: Business and finance * Iso (supermarket), a chain of Danish supermarkets incorporated into the SuperBest chain in 2007 * Iso ...

5832-5:2005 specifications dictate how L-605 is manufactured and tested.

References

Biomaterials Cobalt alloys {{alloy-stub