A short description of nickel alloys

Nickel alloys are high-performance metals, created by combining nickel with other elements such as chromium, copper, iron, molybdenum, and cobalt in different ratios and permutations for a variety of demanding applications in harsh environments such as aerospace and aeronautics; medical, science, military, and oil and gas industries; marine and offshore locations; mining; and chemical processing.

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Why use nickel in these alloys?

Due to its high resistance to heat and corrosion, particularly from alkalis and halogens, pure nickel is highly useful in the chemical industry, as well as for electromagnetic shields and transducers in various sectors.

How are nickel alloys categorised?

The different nickel alloys are classified by their primary alloying elements. The specific type and ratio of alloying with other metals and minerals depend on which of their unique properties are required for dedicated applications, including shape memory, low expansion coefficients, and resistance to high-temperature scaling.

The most common types include nickel-copper, nickel-chromium, nickel-molybdenum, nickel-iron, and nickel-chromium alloys.

What are the special properties of nickel alloys?

For specialist applications with unique characteristics, nickel alloys are created by combining pure nickel in specific ratios and combinations with other minerals. Some of these properties include:

Exceptional corrosion resistance

Nickel does not readily react to corrosive agents and can form a stable oxide layer that forms a surface barrier. 

This quality makes nickel alloys highly resistant to degradation and deterioration in harsh chemical environments, including acids, caustic solutions, and high-temperature gases. 

Chemical, petrochemical, and marine industries, in particular, require nickel alloys that can withstand the corrosive effects of acids, alkali, high-temperature gases, and chlorides in saltwater. This quality is indispensable on equipment like reactors, heat exchangers, and pipelines.

High-temperature strength

This refers to their ability to maintain mechanical integrity, resist creep deformation, and withstand corrosive environments at extreme temperatures. Nickel’s natural resistance to corrosion and oxidation, combined with the ability of alloying elements to form protective oxide layers that shield the surface and strengthen the metal’s crystal structure.

Aerospace, power generation, and nuclear applications demand superior strength and structural integrity under pressure in processing equipment and components like reactors, exhaust systems, and incineration systems, especially at high temperatures.

Ductility and toughness

Aerospace, aeronautics, chemical processing, energy production, manufacturing, and automotive sectors require alloys with exceptional ductility, formability, the capability to endure extreme mechanical stress and pressure without deformation, and toughness when exposed to high temperatures in corrosive conditions.

Ductility describes the material’s ability to be stretched or bent without breaking. Toughness is its ability to absorb energy without fracturing under stress and sudden impact. 

Nickel alloys offer a combination of high tensile strength along with excellent ductility and toughness, enabling them to deform without becoming brittle. This property is essential for avoiding sudden, dangerous component failures in applications such as jet engines and power plants.

Magnetic properties

The magnetic properties of nickel-containing materials are determined by their ferromagnetic nature and indicate how they respond to magnetic fields. Described differently, it is categorised by how easily they can be magnetised and the strength of their magnetic intensity.

Industries such as electronics, medical, automotive, and aerospace need nickel alloys with exceptional magnetic permeability and ease of being magnetised in sensitive magnetic environments. These alloys are used in applications such as inductors, transformers, magnetic shielding, MRI machines, sensors, data storage, transformers, sensitive electronic components, and precise measurements.

Weldability

This is the ability to weld a metal into a satisfactory structure, free of defects like cracks, porosity, or structural weakness,  performing well in its intended service. 

In aerospace, construction, shipbuilding, chemical processing, and power generation, outstanding weldability directly impacts the integrity and performance of components and equipment like pressure vessels, heat exchangers, shipping structures, and turbine or engine components.

It also simplifies manufacturing and the fabrication of complex structures and shapes. Achieving a high-quality weld maintains the crucial mechanical properties of the base metal and prevents costly failures, cracking, porosity, or other defects.

Durability

Nickel alloys have an exceptional ability to withstand harsh conditions, such as high temperatures, extreme pressures, and corrosive environments, for extended periods without weakening or degrading. They maintain their structural integrity and mechanical strength much longer than most other materials, leading to greater longevity of components, increased safety and reliability in critical applications, and reduced maintenance and replacement costs.

Versatility

The excellent corrosion resistance, high strength, and thermal stability give nickel alloys the unique ability to perform well across a wide spectrum of demanding environments. By adjusting their compositions, they have unique benefits and applications, ranging from deep-sea mining to technology and aerospace.

What are the main types of nickel alloys?

Nickel alloys are broadly categorised into several types, based on their composition and properties, of which the following are the most common:

Nickel-Copper Alloys

Examples:

Monel, Cupronickel, Constantan, and Alloy 400

Main characteristics:

• Excellent corrosion resistance in alkaline, non-oxidising, chloride, marine environments, and in saltwater.
• Good mechanical strength.
•  Great ductility.
• High thermal stability
• Biofouling resistance.

Main industries:

• Marine engineering,
• Desalination plants,
• Offshore oil and gas, and
• The chemical industry.

Common applications:

• Seawater, chemical, petroleum, oil & gas, and hydraulic pipelines,
• Bilge and ballast water systems,
• Heat exchangers,
• Desalination condensers and evaporators,
•  Coolers,
• High-pressure heaters.

Nickel-Chromium Alloys

Examples:

Inconel, Nichrome, Chromell, Alloy 800, Hastelloy, and certain grades of stainless steel.

Main characteristics:

• Exceptional chemical resistance
• Oxidation and rust resistance,
• Electrical resistance,
• High-temperature performance, and
• High strength.

Main industries:

• Aerospace,
• Chemical processing,
• Power generation,
• Oil and gas, and
• Automotive industries.

Common applications:

•  Heating elements for toasters and electric heaters,
• Chemical processing and transporting,
• Oil & gas production and transportation,
• Marine and offshore equipment,
• Propellers,
• Turbine blades,
• Scrubbers,
• Food and beverage production,
• Surgical and dental restorations. 

Nickel-Iron Alloys

Examples:

Invar, Permalloy, Incoloy, and certain grades of stainless steel. Natural nickel-iron alloys include Kamacite and Taenite (from meteorites).

Main characteristics:

• High magnetic permeability
• Very low thermal expansion,
• Creep resistance, and
• Corrosion resistance.

Main industries:

• Medical,
• Aerospace,
• Electronics,
• Energy,
• Automotive.

Common applications:

• Electronic transformers,
• Magnetic shielding,
• Automotive and aeronautical sensors,
• Aerospace equipment,
• Medical devices such as MRI machines,
• Specialised industrial machinery,
• Nuclear reactors,
• Electroplating.

Nickel-Molybdenum Alloys

Examples:

Hastelloy, Alloy B-2, Alloy B-3, and N-12MV

Main characteristics:

• Outstanding resistance to pitting, stress corrosion, and cracking,
• Corrosion resistance to both reducing and oxidising acids (hydrochloric and sulfuric acids), and
• Less susceptible to weld zone corrosion.

Main industries:

• Oil and gas,
• Chemical processing,
• Medical,
• Aerospace.

Common applications:

•  Pumps,
• Valves,
• Piping,
• Ducting,
• Heat exchangers,
• Marine hardware,
• Pharmaceutical and chemical production, and
• Power generation systems.

Superalloys

Examples:  

Inconel, Hastelloy, and Waspaloy; cobalt-based alloys like Haynes and Stellite; and iron-based alloys such as Incoloy and A286.

Composition:

Designed for extreme environments by alloying nickel and elements such as cobalt, tungsten, molybdenum, and chromium.

Main characteristics:

• Excellent mechanical properties,
• Superior oxidation resistance,
• Exceptional heat resistance,
• Wear resistance, and
• High strength.

Main industries:

• Manufacturing,
• Aerospace,
• Energy,
• Marine engineering,
• Nuclear,
• Power generation,
• Oil & gas.

Common applications:

• Ducting and piping in jet and gas turbine engines, 
• Ducting, piping and exhaust systems in nuclear reactors,
• Combustion chambers, 
• Turbine blades,
• Heat exchangers,
• Chemical reaction vessels,
• Medical and surgical instruments,
• Automotive parts

Visit our contact page to get in touch or alternatively, email us at sales@specialmetalalloys.co.uk for more information on nickel alloys and how we can help you.