Why high temperature or the impact would make a strong magnet demagnetization?
Some objects made of steel, such as needles, screwdriver, etc will show after contact with the powerful magnet magnetic, this phenomenon is called magnetization.
As we know, current can stimulate magnetic field, electric solenoid external magnetic field is very similar with the powerful magnet bar.
It is this, a lot of material in magnetic field can be more or less to be magnetized.
Of course, we know that iron, cobalt, nickel and their alloy, there are some oxide, after magnetization of magnetic much stronger than other substances, it turns out that the structure of this kind of material is different with other substances, they itself is made up of many small regions that have been magnetized, these small areas of magnetization is called the 'domain'.
After magnetization of the material, once the orderly arrangement of the magnetic domain was damaged, back to the chaotic state, will lose magnetic objects.
Powerful magnets for heating at high temperature, the process by which a object interior particles is very severe, for the change in the direction of magnetic domain provides the energy and lead to its orderly arrangement, had been disrupted, which would make it lose magnetism.
In fact, in addition to heating, violent vibration, the action of alternating magnetic field, can also disturb originally ordered particles, lose a strong magnet magnetic, which is frequently used in industrial degaussing alternating magnetic field to make objects.