Mu Metal specifications
Specifications : ASTM A-753 Alloy 4, MIL N-14411C Composition.
Mu metal is a 80 % Nickel, 4.5 % Molybdenum, balance Iron, soft ferromagnetic alloy which means that it does not retain a field after the removal of an external magnetizing force.
Mu-metal ® offers exceptionally high initial and maximum permeability with minimum hysteresis loss. It also has very low coercive force, very low core losses and a low remanence.
To reach the required magnetic performance mumetal needs to undergo a full final heat treatment in a dry hydrogen atmosphere furnace with a dewpoint of <-40 Deg C at 1100-1180 Deg C for 2-4 hours.This heat treatment increases the magnetic permeability by about 40 times.
The annealing process increases the mumetal ® grain size and hence the magnetic domains. However these enlarged grains are susceptible to severe shocks or further mechanical working and the permeability will decrease in these areas. This can be rectified by a re-anneal.
The high permeability of mumetal ® provides a low reluctance path for magnetic flux leading to its use in magnetic shields against DC and AC fields.
Typical Final Annealed Properties
Hardness : 120 Hv
Tensile Strength : 530 MPa
0.2 % Yield Strength : 160 MPa
Elongation : 45 %
Typical Magnetic Properties(DC) after final heat treatment
Permeability Mumax : 350000-500000
Saturation Induction : 0.76 T
Coercive Force : 0.6 A/m
These high levels of mumetal ® permeability compare to several thousand for ordinary steel
This site is ran and supported by Magnetic Shields Limited
Need help with a magnetic shielding project? Please visit our company site here
D5 Creation
Hello,
I would like to know the permeability of the mu metals you carry in the MHz region. I am interested in 2 MHz and their hysteresis loss at this frequency.
Thanks
Kamal Hadidi
Dear Sir,
I enclose some sample data of mu metal curves at lower frequency which I believe displays the drop in permeability and what you are likely to expect in the MHz range. Unfortunately there has been no research at such a high frequency by any of the material manufacturers that I am aware of, which is primarily due to the poor efficiency of this material in this range (MuMax will be in the hundreds)
Sorry I cannot be of more assistance.
Kind Regards,