It all depends on the agent. It happened both ways for me in the past. Since BR has interline agreement with AS, they usually check your luggage through if the final leg is on the same ticket. If they are on separate tickets like in your case, they don't have to do that. It will come down to whether the agent will do you a favor or not. Most AS/QX agents are nice people, but I won't bet money in your case.

Good luck!