A comparison of microstructural developments in TLP diffusion bonds made using ODS Ni alloy

The presence of a dispersion of Y2O3 particles and an elongated grain structure with an aspect ratio of greater than 5 gives oxide dispersion strengthened alloys excellent creep properties at elevated temperatures. Therefore, when engineering components are fabricated using ODS alloys, consideration must be given to the joining technique used during manufacture. In this study, a diffusion bonding technique is used to join a Ni-based ODS alloy, MA 758, using two different metal interlayers. The research investigates the effect of interlayer composition, bonding time and the use of post-bond heat treatments on compositional and microstructural homogeneity of the joint region. The influences of parent alloy grain size were found to be significant on the diffusion bonding process using both Ni-Cr-Fe-B-Si and Ni-P interlayers. Diffusion of elements from the parent alloy into the liquid interlayer has a significant effect on the rate of isothermal solidification when using Ni-P interlayers.