We continue the examination of important elements in heat treatment and metallurgy. This time our focus is on nickel.
Nickel (Chemical symbol: Ni)
The Devil's Copper
Nickel was discovered in Sweden by Axel Fredrik Cronstedt in 1751. It was contained in a mineral named "kupfernickel," German for "Devil's copper." This mineral was valued at the time for coloring glass green. Much earlier – around 1500 B.C. – the Chinese referred to "white copper" (baitong), which is thought to be an alloy of nickel and silver.
Nickel is the fifth-most-abundant element on (and in) earth and one of the most widely used metals in the world (Fig. 1). According to the Nickel Institute, the metal is used in over 300,000 different products. Most often it is found in steels and metal alloys, but it is also used in the production of batteries and permanent magnets. It is one of only four elements that are magnetic at or near room temperature; the others being iron, cobalt and gadolinium. Its Curie temperature is 355°C (671°F), meaning that nickel is non-magnetic above this temperature.
Ironically, pure nickel is reactive with oxygen but becomes very stable when combined with iron, and its most common use is in corrosion-resistant stainless steel. In fact, 65% of all nickel is used as an alloy of stainless steel. For example, 300 series (austenitic stainless steels) are non-magnetic and contain high percentages of chromium and nickel (and relatively low levels of carbon). They are important for their formability and resistance to corrosion.
The price of nickel is volatile. It varies widely depending on economic activity and corresponding demand for stainless steel. It has ranged from $4 to $23 per pound in recent years (Fig. 2).
The Philippines, Indonesia, Russia, Canada and Australia are the world's largest producers of nickel. The Riddle, Ore., mine in the U.S. produced until 1987, at which time it closed. The Eagle mine project is a new nickel mine in Michigan's Upper Peninsula that started operations in the third quarter of 2014. The Eagle Mine produced 18,000 tons in its first year. Known land-based resources averaging 1% nickel or greater contain at least 130 million tons of nickel.
Here are some physical characteristics of nickel.
Melting point: 1728 K (1455°C, 2651°F)
Boiling point: 3003 K (2730°C, 4946°F)
Density at standard conditions: 8.908 g/cm3
Heat of fusion: 17.48 kJ/mole
Heat of vaporization: 379 kJ/mole
Molar heat capacity: 26.07 J/(mole·K)