CHARACTERIZATION OF DIFFUSION BONDS FORMED BETWEEN TI-6AL-4V AND TITANIUM ALUMINIDE SUPER ALPHA-2

Isostatic diffusion bonds were produced between Ti-6Al-4V and Super Al pha-2 sheet materials at temperatures of 920-940 degrees C and pressur es of 6-10 MPa. The diffusion bonds were evaluated using optical micro scopy, lap shear testing and scanning electron microscopy of the lap s hear fracture faces. The results of X-ray microanalysis carried out on the bond interface region showed that substantial diffusion of niobiu m and molybdenum had occurred from the Super Alpha-2 to the Ti-6Al-4V. This caused a local suppression of the beta transus in the Ti-4Al-4V alloy and on subsequent cooling the beta phase decomposed to give a mi crostructure of fine acicular alpha phase and retained beta phase in t he bond region. (C) 1996 The Institute of Materials.