Defined by ASTM International as metals that have more nickel content by weight than any other element, nickel alloys are sometimes also described as alloys containing less than 50% iron and more nickel than any other alloy element, other than iron. With a total worldwide production of 300,000 tonnes, nickel alloys represent only a small fraction of the total production of stainless steels. Their importance for industry and society, however, is far greater.
Characterised by excellent corrosion resistance, ability to withstand high temperatures, and special magnetic and thermal expansion properties, nickel alloys play a vital role in helping to provide energy, a cleaner environment, improved health and many other services for the expanding population.
In a recent article published in Stainless Steel World News, Gary Coates, Market Development and Technical Manager at the Nickel Institute, offered a host of arguments for why nickel alloys are essential for both existing and developing technologies. In the Nickel Institute’s estimate, about 50% of all nickel alloys end up in aqueous-corrosion applications, about 40% in high-temperature applications including aerospace, with the balance going to specialized applications, notably in electronics. Typically, nickel alloys are used where stainless steels – in terms of performance – are inferior to them or entirely unsuitable. Crucially, the majority of industries and sectors heavily dependent on nickel alloys are responsible for the production of commodities and provision of services without which our lives are impossible to imagine. They include the oil & gas, chemical & petrochemical, and power generation industries as well as the destruction of hazardous waste.
The other end of the end-user spectrum is populated by niche industries such as healthcare. As Gary Coates explains in his article, “longer human life expectancy brings an increased need for medical procedures along with an increasing need for different and complex implants for various conditions linked to ageing. Nickel alloys have a long history of use in implants and have made important contributions to the quality of life of millions of people. A common implant is a ‘stent’ – a small mesh tube made from a nickel-titanium alloy, used to keep arteries open and often used in the treatment of coronary artery blockages. The alloy has shape-memory or ‘superelastic’ properties. Each year in the United States alone more than one million people undergo an operation called angioplasty to treat coronary heart disease. Patients have a 90% long-term success rate when treatment includes an antibacterial-coated nickel-titanium stent. Prior to the advent of this technology, doctors performing angioplasty without stents could expect only a 60% success rate.”
The need for nickel alloys and their benefits are therefore more than apparent. To further explore this topic, see the November issue of Stainless Steel World News, pp. 8–9, or read the PDF version of the article.
Photo: A piece of nickel. Photo © Materialscientist