Demanding applications requiring high corrosion resistance, or high temperature resistance often require nickel alloys. The family of nickel and its alloys includes: various pure nickel, binary alloys of Ni-Cu, Ni-Si or Ni-Mo, ternary alloys of the Ni-Cr-Fe, Ni-Cr-Mo type, etc. and superalloys.
Commercial pure nickel is characterized by excellent corrosion resistance in reducing environments.
Nickel and copper form a solid solution throughout the range of compositions. These alloys can therefore only be hardened by strain hardening and exhibit excellent corrosion resistance, better than pure nickel in reducing atmospheres and better than copper in oxidizing atmospheres.
Nickel and chromium alloys, nickel, chromium and iron alloys as well as nickel and molybdenum alloys are alloys exhibiting high resistance of mechanical properties to temperature.
Nickel is part of the composition of several families of metal alloys. Apart from stainless steels (which do not belong to the family of nickel alloys but to that of steels), nickel alloys can be classified into three categories:
Iron-nickel alloys: they are used for their sometimes surprising physical properties. For example, invar, an iron-nickel alloy containing 36% nickel (FeNi36), is virtually unilateral below 200 ° C. It is used there in cryogenics (tank of LNG carriers), in laser physics (structural elements) or in cathode-ray television screens ("shadow mask"). The physical properties of iron-nickel alloys used are the magnetic properties (alloys with high magnetic permeability, alloys with low Curie point, magnetostrictive alloys), elastic (alloys with very low thermoelastic coefficient), as well as their extraordinary expansion properties. (“indilatable” or controlled expansion alloys) Copper-nickel alloys (cupronickels): they have very good resistance to corrosion in acidic or marine environments, as well as good formability and weldability.
Superalloys: this is how we call a family of alloys with a complex composition, based on nickel (or cobalt), exhibiting excellent resistance to dry corrosion at high temperature and very good mechanical properties (elastic limit high, creep resistance). These are the materials of choice for turbojets (aeronautics) and certain boilers. The development of these alloys has accompanied that of aircraft engines since the middle of the 20th century.
Nickel is also used in the cathode of Nickel-Cadmium,
Nickel-Metal Hydride and Nickel-Zinc alkaline batteries.
Electric Guitar Strings: Nickel is used for certain types of strings.
It is useful to locate the uses of nickel in the different types of metallurgical products:
10% is used in the unalloyed state, essentially in the form of electrolytic plating;
10% is used in nickel steels and iron-nickel alloys;
10% is used in corrosion resistant nickel base superalloys and super refractory alloys;
60% are used in stainless alloys;
5% are employed in the foundry;
5% are used in the form of chemicals and coins.
Like many other metals, the applications of pure nickel are much smaller than those as an alloy with other components.
- Maraging or age hardening steel
Main representative of steels with high mechanical characteristics, it consists of 18% nickel, 8% cobalt, 4% molybdenum and 0.03% carbon, as well as various other elements such as: manganese, titanium , aluminum or silicon.
- Le Constantan (registered name)
It is an alloy of copper and nickel used among other things for making electrical resistance wires.
It is an iron alloy containing 36% nickel and whose coefficient of expansion is close to 0. It is used in watchmaking and in all areas in which parts are subjected to temperature variations.
For many applications, it has been necessary to develop alloys which retain acceptable mechanical properties at high temperature (between 700 and 1000 ° C.) without degrading by oxidation.
Generic name of complex alloys exhibiting very good resistance at high temperature and high pressure to oxidation, corrosion, creep and cyclic stresses (mechanical or thermal). They are generally intended for aeronautics, chemical reactors, cryogenics and thermal power stations.
It is the ability of an alloy to benefit from the effects of quenching. This ability is often determined by the grain size of the steel and the quality of its production.