Nickel and nickel alloys
Nickel alloys divided by application:
| In terms of application, various nickel alloys can be divided into | |
|---|---|
| Structural alloys | |
| Superalloys, Corrosion and heat resistant nickel alloys, cobalt alloys | |
| Special alloys, including magnetically soft alloys and shape memory alloys |
Properties of Nickel
- Suitable for hot- and cold working
- Good mechanical properties in high temperature (below 5000C)
- Corrosion resistant
- Very important alloy addition and metallic matrix
- Strongly ferromagnetic at ambient temperature
Among the major industrial metals, nickel is one of the most versatile. It is valued for its heat and corrosion resistance. It is an important alloy addition in ferrous and nonferrous alloys.
Nickel-base alloys play a vital role in the modern industry because of their ability to operate in a wide variety of severe conditions, often involving factors like corrosive environment, high temperature, and high stress.
Nickel has good resistance to corrosion in a normal atmosphere, in both fresh and salt waters. Moreover, it resists organic acids and caustic alkalies. It is not resistant however to phosphoric and nitric acids, as well as sulfur compounds.
About 70% of nickel’s world production is used in irons and steels, mostly stainless steel. Nickel alloys consume about 13% of whole input, and more or less 10% is used for platering. Pure nickel is used in electronics, in a food industry, in research equipment and, notably, for components in aviation and aeronautics.
Physical and Mechanical Properties of Nickel
- The number in periodic table – 28
- Atomic weight – 58,6934
- A transition metal, 10th group, 4th series in the periodic table
- Amount of stable isotopes – 5
- Density – 8,902 g/cm3
- Melting point – 14530C
- Boiling point – 27300C
- Tensile strength, when softened – Rm = 450 MPa; elongation A=45%. Tensile strength can be enhanced by suitable working.
- It shows excellent properties at elevated temperatures (~5000C)
- Hardness of pure nickel – 35 HRB. Cold work and impurities increase the hardness.
- Curie point - 3580C
Interesting facts:
Nickel is (along with iron and cobalt) one of three major elements, that are strongly ferromagnetic at ambient temperature. While pure nickel is rarely used itself this way, nickel-containing alloys are fairly often utilized as a magnetic material.
Suitable working, like hot rolling, cold rolling, cold drawing and annealing can greatly enhance tensile strength of nickel bars, rods and wires.
Nickel alloys divided by application:
In terms of application, various nickel alloys can be divided into:
- Structural alloys
- Corrosion, creep and heat resistant nickel alloys
- Superalloys
- Resistor alloys
- Special alloys, including magnetically soft alloys and shape memory alloys
History of Nickel
When was nickel discovered? How was it used? What nickel has incommon with meteorites? Enjoy the short history of nickel.
Nickel alloys in antiquity
Although nickel itself was not known to mankind for much of our history, the unique properties of corrosion-resistant and durable iron-nickel alloys have been recognized since ancient times. When metallurgy was unknown, a source of such unique material were meteorites.
One category of such guests from outer-space are iron meteorites, which are largely composed of iron-nickel alloy (with an example of the largest meteorite identified on Earth, found in Namibia and named Hoba). The technology of the time allowed to produce valuable goods from this material.
The ancients were no doubt strongly impressed by objects falling down from the sky. No wonder that archeologists find knives and other tools made of meteoric iron in royal tombs. For example, such a knife was found in Tutankhamen’s tomb. Other ancient civilizations, including Shang China, Hatti, and Sumer, also produced similar items.
The first place, where nickel was consciously used, was probably China. Báitóng (which in English means „white copper”) was used there to mint coins. Interestingly, nickel is also used in coinage today.
Therefore, although nickel is present in artifacts of thousands of years, the true value of this metal was unknown. This changed with the industrial revolution.
The dawn of nickel in the industrial era
For the first time, the term "nickel" appeared in the documents in 1754, in the work "Continuation of results and experiments on cobalt ore". The author incorrectly classified nickel as semi-metal, and this is due to the inadequate purity of the sample.
The properties of nickel were correctly described in 1804 by J.B. Richter. Shortly thereafter the USA, along with other countries, started to use nickel as a component of coins.
Demand for nickel skyrocketed in the70s and 80s of the XIX century, when the beneficial properties of nickel-containing steels were discovered and the first nickel coatings were developed. Soon, this metal was used in shipbuilding.
From the beginning of the previous century to this day continues the development of corrosion- and heat-resistant superalloys, which are a crucial component of jet engines, and thus play an important role in the world we live in.