Methods for deposition of an aluminide coating on an alloy component positioned within a coating compartment of a retort chamber are provided. According to the method, the coating compartment is purged with an inert gas via a first gas line; a positive pressure is created within the coating compartment utilizing the inert gas; the coating compartment is heated to a deposition temperature; and at least one reactant gas is introduced into the coating compartment while at the positive pressure and the deposition temperature to form an aluminide coating on a surface of the alloy component. Retort coating apparatus are also provided.