metal bracket on hard drive magnets ?

Because NdFeB magnets corrode in air fairly quickly, nickel is electroplated onto the magnet and bracket.
These magnets are quite powerful, almost dangerous if they are strong enough. This poses a threat to computers, seeing as most data is magnetically sensitive (at least to some degree). To combat this problem, computer engineers make the magnet’s brackets out of an IRON, NICKEL and MOLYBDENUM based alloy called a permalloy! Permalloy has an extremely high magnetic permittivity, meaning it will stop most magnetic fields.

I got this from The Irrationalist's web blog.