One of the most amazing phenomena of nature is the manifestation of magnetism in some materials. Permanent magnets are known since ancient times. Before the great discoveries in the field of electricity, permanent magnets were actively used by physicians. Over time, people learned to create artificial magnets by placing iron alloy products in magnetic fields. Permanent magnets are frequently used in industry, in various fields, such as electrical engineering, computer technologies, transportation, navigation, medicine, biology, astronomy etc. The main application of magnets is in electrical engineering, radio engineering, instrumentation, automation and tele-mechanics. For example, without magnetic materials, electrification would be impossible because generators, transformers for power transmission, and speakers for electric motors, telephones, radios, and televisions would be used for power generation.
The active introduction of permanent magnets in the sphere of human activity stimulates inventing and creating new ferromagnetic alloys with improved magnetic characteristics.
Pure magnetic metals
Iron, cobalt, nickel, gadolinium – only these four metals are pure and magnetic at ambient temperature. This property is called ferromagnetism. All rare earths alloys used industrially for permanent magnets contain these metals.
However, there are 9 metals that have strong magnetic properties, being able to be attracted by magnets and they themselves are able to become magnets: iron, cobalt, nickel, but also gadolinium, terbium, dysprosium, holmium, erbium, thulium. Aluminium, platinum, chromium, titanium, vanadium, manganese are very weakly attracted by magnet. They magnetize so little that it is impossible to detect their magnetic properties without special tools.
Ferromagnetic metals are strongly attracted by objects with magnetic fields and can keep their magnetic properties after the magnet is removed from them. They are used to create permanent magnets. The main ferromagnetic metals are iron, nickel, cobalt, gadolinium, and dysprosium. If a piece of ferromagnetic metal is held next to a magnet, a strong enough attraction will be felt.
Ferromagnetic alloys are materials such as steel, which contain ferromagnetic metals. Steels is a combination of iron and several other metals and is harder than iron. Due to this hardness, steel can retain its magnetism longer than iron. When heated at high temperature, steel loses its magnetic properties. This will also happen to ferromagnetic metals such as nickel.
Ferrimagnetic materials are ferrite, magnetite, and magnesium. They all have as main component iron oxides, as well as oxides of other metals. Lodestone is magnetite that is naturally magnetized. Magnetite is attracted to magnetic fields, but usually does not magnetize itself. Ferrimagnetic materials are similar to ferromagnets, but with a smaller magnetic attraction.
Paramagnetic metals are weakly attracted to magnet and do not retain their magnetic properties when removed from the magnet. These include copper, aluminium, and platinum. The magnetic properties of paramagnetic metals depend on temperature and aluminium, uranium and platinum become more attractive for the magnetic fields when they are very cold. Paramagnetic substances have much lower attractive forces for magnets than ferromagnetic materials and very sensitive instruments are needed to measure magnetic attraction.
Is stainless steel magnetic?
There are over 120 different types of stainless steel! If an alloy contains at least 12% chromium, it can be considered rust-resistant stainless steel. Most stainless steels are made of austenitic alloys and are only slightly magnetic. Steel …….