Ferromagnetic materials are strongly attracted by a magnetic force. The elements iron (Fe), nickel (Ni), and cobalt (Co) are the most commonly available and attracted elements. Steel is also very susceptible or attracted to a magnetic field because it is ferromagnetic as an alloy of iron and other metals.
Ferromagnetic materials are attracted to magnets because their electrons spin and the resulting “magnetic moments” align easily, and retain that alignment even without an external magnetic field. Ferromagnetic materials such as iron, nickel and cobalt are therefore attracted to magnets, as well as rare-earth metals like gadolinium, neodymium and samarium.
We all know that magnets attract each other at opposite poles and repel at like poles. But exactly what types of metals do they attract? Neodymium magnets are known as the strongest magnet material available and have the highest holding strength to these metals. They are called ferromagnetic metals containing mainly iron, nickel and rare earth alloys. On the contrary, paramagnetism is the very weak attraction between other metals and magnets for which you can barely notice.
Alloys made from these materials are also attracted to magnets, so stainless steel with substantial amounts of iron in (as opposed to chromium, for example) is attracted to magnets. Other ferromagnetic alloys include awaruite (nickel and iron), wairauite (cobalt and iron), alnico (cobalt, iron, nickel, aluminum, titanium and copper) and chromindur (chromium, cobalt and iron). Essentially, any alloy composed of ferromagnetic materials will also be magnetic.
The most commonly used metals to be attracted by magnets or magnetic devices are ferrous metals which contain iron and iron alloys. Steels, for examples, are widely applied and can be easily handled by lifting devices containing neodymium magnets. Due to the fact that these iron electrons and their magnetic fields can be easily aligned with external magnetic field, it is easy for neodymium magnets to attract to them. And based on the same theory, neodymium magnets composed of iron can be induced by powerful magnetic field and retain the magnetism. Stainless steel alloys on the other hand do not have this property and cannot be attracted to a magnet. Elemental nickel and some nickel alloys are also ferromagnetic, such as Aluminum-Cobalt-Nickel (alnico) magnets. The key for them to attract to magnets is their alloy composition or which other elements do they have. The nickel coins are not ferromagnetic because they contain majority of copper and a smaller portion of nickel.
Metals like aluminum, copper and gold show paramagnetism or weakly attractive. When placed in a magnetic field or close to a magnet, such metals create their own magnetic fields that weakly attract them to the magnet and do not persist when the external magnetic field is removed.
Paramagnetic metals have a weaker attraction to magnets than ferromagnetic metals, and they don't retain their magnetic properties in the absence of a magnetic field. Paramagnetic metals include:
Some materials are classed as ferrimagnetic. This occurs when an ionic compound has two lattices of material with opposing magnetic moments, but the two are not completely balanced, leading to a net magnetization. Magnetite provides an example of this type of magnetism, and it was originally considered a ferromagnetic material because of the similarities between these two types of magnetism. However, many ferrimagnetic materials are ceramics rather than metals.
Diamagnetic metals are actually repelled by magnets rather than attracted to them, and usually weakly. Materials are classed as diamagnetic when their magnetic moments act in opposition to the field applied rather than to enhance it. These materials include silver, lead, mercury and copper.
Thus, it is important to understand your material before purchasing any magnet material, mounting magnets or lifting magnets. It is best to find out the compositions of your metal material for which certain contents, i.e. carbon, significantly affect the magnet pull strength.
AH MAGNET is an IATF16949, ISO9001, ISO14001 and ISO45001 accredited manufacturer of all kinds of high performance neodymium magnets and magnetic assemblies with over 30 years of experience in the field.
We are committed to manufacturing a wide variety of permanent rare earth magnets and assemblies to choose from such as N, M, H, SH, UH, AH and EH grades. All NdFeB magnet products are used in a wide variety of applications, from servo motors, stepper motors, brushless motors to permanent magnet synchronous motors. If you are interested in our products, please feel free to contact us!