Analysis of microstrctures and properties of Ti₂AlNb intermetallic compound inertia fricrion welded joints

Study on welding test of Ti₂AlNb intermetallic compound was carried out by the inertial friction welding procedure. Microstructure of welded and welded heat treatment joint was observed by SEM.The microhardness variation trend of the joint was analyzed. The results show that base metal of Ti₂AlNb intermetallic compound trial comprise α₂+B2+O three phases organization. The α₂ phase is distributed in the grain boundary of original B2 phase with intermittent meshes and blocks. The lamellar O phase is distributed in the base metal of B2 phase; The friction welding joint has obvious partition. The weld zoon is composed of single equiaxed grain of B2 phase and grain are uniformly fine. The close to the weld zone of TMAZ is consisted of B2+α₂ phase orgainzaton. The α₂ phase is directional distribution along the direction of friction. The TMAZ further away from the weld zone is comprised similar of B2+O+α₂ three phases organization. Heat treatment joint weld zone after welded composed of B2+O two phase organization and accompanied suspect twinning. The TMAZ consist of B2+O+α₂ three phases organization. The B2 phase of original black stripe in the near-weld zone has transformed into the massive O phase and the rest of B2 phase has transformed into B2+O phase lath beam. Microstructure of heat affected zone is similar with base metal, but the thickness of O+B2 phase lath beam is a finer. The microhardness of weld zone of welded joint and heat treatment joint after welded is the highest. With the position transitting to the base metal, the hardness decreases gradually.