Whereas firearms and ammunition have to be separated in different baggage and kept apart, broadheads are treated the same as knives and as long as they are in your checked and locked baggage, there is no problem with carrying them. Of course you cannot carry them on in any situation but they can be brought along as checked baggage.
I do recommend taking them off your arrows and storing separately not only to protect the broadheads and blades from dulling but also to protect your other equipment in the case they are stored in. Baggage handlers are very rough with equipment and if a broadhead tipped arrow or loose broadhead was to get loose and move around inside a case or baggage it could cause some serious damage. You can store them in your bow case with your bow, but I do recommend leaving them off the arrows and packaged securely and separately from your arrows. It would probably be best to protect the edges of the blades to disassemble the heads and keep the blades in their own packaging as well, definitely do not want the blades loose and exposed for any reason. Just pack the heads with your knives and other equipment and check it in and you should be fine, but I am sure you will need to lock your case as well. Good luck and have a great hunt and look forward to hearing of your success!