Nd-Fe-B magnets - found that new magnets contain no rare-earth elements.

In 1840s, British physicist James Jawer found that when placed in a magnetic field, iron based magnetic materials would change their shape, but the volume remained the same. This phenomenon is known as "Joule magnetostriction". All the magnets have shown this characteristic in the 175 years since its discovery.




According to ScienceDaily, a new type of magnet has been discovered by researchers at Temple University and University of Maryland. They heat the particular iron base alloy in the furnace to about 760 degrees centigrade and last for 30 minutes, and then quickly cool it to room temperature, when the material is placed in a magnetic field, which shows a non Joule magnetostrictive behavior (expansion).




The researchers point out that the conventional magnets can only be used as actuators in one direction by the Joule magnetostriction. Even in two directions, a lot of heavy magnets are needed, which will increase the volume and reduce the efficiency. Instead of Joule magnetostrictive magnets can expand in all directions at the same time, so it is easy to make compact omnidirectional actuators.




Because these new magnets also have energy saving features, they can be used to create a new generation of sensors and actuators with low heat loss, which are used in aerospace, automobile, biomedicine, defense, space exploration and robotics.




The researchers also said that the new magnet does not contain rare earth elements, so it can replace the existing rare earth based magnetostrictive materials with high cost but low mechanical properties. It