Microstructure and properties of Al₂O₃/CuSnTi+B/Ti-6Al-4V alloy joint

Al₂O₃ and Ti-6Al-4V alloy was brazed at brazing temperature of 910°C and holding time of 10min using Cu-Sn-Ti+B composite brazing filler metal, which was fabricated by adding B powder to Cu-21Sn-12Ti at different mass fractions. The effect of TiB whiskers synthesized in situ on the microstructure and mechanical properties of Al₂O₃/Ti-6Al-4V alloy joint was investigated. The TiB whiskers synthesized in situ during brazing were distributed evenly in Ti₂Cu. The fine and compact joints of Al₂O₃/Ti-6Al-4V alloy could be obtained when the volume fraction of TiB was <40% in joint, Ti₂(Cu, Al) intermetallics in zoneIIof joint accordingly increased, their distribution became continuous, the distribution area of TiB, i.e. zoneIIIbecame wider and the dissolved Ti, Al elements from Ti-6Al-4V alloy into filler metal increased with increasing the amount of TiB. The shear strength of joints at room temperature increased and then decreased with the increase of TiB. The shear strength of joint reached the maximum value of 70.1 MPa at the amount of TiB of 20%(in volume).