Abstract (EN):
TiAl alloys are good candidates for several applications in the aerospace and automobile industry due to their mechanical properties. Several techniques have been reported to join TiAl alloys, among these diffusion bonding is the most reported one. The introduction of interlayer materials with similar or dissimilar chemical composition of the parts to be joined seems to offer a promising method for and will contribute to enlarge the industrial application of TiAl alloys. In this study, we used interlayer materials, namely Ni/Al sputtered nanolayers and Ti and/or Ni foils, to diffusion bond TiAl and achieve high strength joints. The Ni/Al nanolayers were deposited by d.c. magnetron sputtering onto TiAl. Joining was performed at 800 and 900°C for 60 or 30 minutes. For some joining experiments we combined the Ni/Al nanolayers with Ti and Ni foils, to fill the bond gap and improve the contact between faying surfaces. Joints performed with 14 and 30 nm period nanolayers revealed a sound bond, while for 5 nm porosity and cracks were observed inside the interlayer thin film. Sound joints were also achieved with a combination of the nanolayer thin films and Ti/Ni/Ti thin foils. Nevertheless, several AlNiTi intermetallic compounds are always formed in the interface region. The use of thin foils drastically reduced the shear strength of the joint.
Language:
English
Type (Professor's evaluation):
Scientific