An Hf-containing alloy was selected as a interlayer for brazing and transient-liquid-phase bonding of single crystal superalloy, in which Hf diffused from the bond to the matrix phase. The object was to determine the diffusion behaviour of Hf in two matrix phases of superalloy, the Ni-rich solid solution (γ) and intermetallic compound (Ni3Al).

Diffusion Behaviour of Hf in Ni and Ni3Al. Ma, S., Zheng, Y.: Chinese Journal of Materials Research, 1996, 10[2], 149-52

Figure 16

Hydrogen permeation flux in Ni72Al19.9Cr8B0.1

Curves, from top to bottom, for 48, 85 and 170µm