Dual alloy turbine rotors and methods for manufacturing the same are provided. The dual alloy turbine rotor comprises an assembled blade ring and a hub bonded to the assembled blade ring. The assembled blade ring comprises a first alloy selected from the group consisting of a single crystal alloy, a directionally solidified alloy, or an equi-axed alloy. The hub comprises a second alloy. The method comprises positioning a hub within a blade ring to define an interface between the hub and the blade ring. The interface is a non-contacting interface or a contacting interface. The interface is enclosed by a pair of diaphragms. The interface is vacuum sealed. The blade ring is bonded to the hub after the vacuum sealing step.