Carbide ballnose sharpening

[spluppit]

Yes of course they can be sharpened. It's very unlikely to be cost effective though. You can get 2mm ball nose in various forms from somewhere like apt for a fiver or less and the quality is perfectly usable.

I'm a little surprised you managed to make a carbide end mill glow red without it breaking especially one that small. Are you using a router style machine and with a high rpm spindle? The chances are that cutter will be totally foobared.