Can INVAR alloy be used as a magnetic core?
Invar can be used as magnetic core material, but there are
better choices. Invar is alloyed for its thermal stability. It is
iron with a good percentage of nickel. Remember that magnetic core
material is usually laminated or is "powdered" in a way to
electrically isolate the "bits" of core material so eddy currents
will be reduced. A link is posted to the article on Invar put up by
our friends at Wikipedia, where knowledge is free.