Diffusion Bonding Of Ti-48A1-2Mn-2Nb (at. %)

Abstract

AbstractThe diffusion bonding behaviour of Ti-48at.%Al-2at.%Mn-2at.%Nb has been studied as a function of temperature (in the range 1200–1350°C), time (15–45 minutes) and starting microstructure (lamellar, duplex and near γ) at constant bonding pressure of 10 MPa. It was found, that under the above conditions, small twin related γ grains, approximately 10–20 μm in size, nucleated at the original interface and grew into the matrix forming a double necklace grain structure. Particles of α2 were observed around the interface, the formation of α2 particles was believed to be related to oxygen partitioning and stabilisation effects from dissolved oxide films during the bonding process. Evidence for this mechanism was obtained from parallel electron energy loss spectroscopy (PEELS), which identified oxygen partitioning in the α2 particles. For the fully lamellar structure bonded at 1250°C for 45 minutes the failure strength of the bond was found to be 250 MPa, approximately 50 MPa lower than the failure strength of the base material.