Abstract: Transient liquid phase (TLP) bonding is a joining process in which a liquid-forming interlayer is placed between the substrates to be joined. At the bonding temperature, the interlayer initially liquates. Subsequently, interdiffusion between the liquid interlayer and the adjacent substrates results in a change in the overall composition of the joint, such that isothermal resolidification of the joint takes place. Standard models of the TLP process assume the sequential occurrence of discrete dissolution, isothermal solidification, and homogenization processes. This study uses edge-on transmission electron microscopy investigations to challenge the general applicability of such standard models to the TLP bonding of a variety of systems involving the B2 type intermetallic compound NiAl as a substrate material. This article considers the formation of boride phases apparently at the bonding temperature in NiAl/Ni-Si-B/Ni bonds. The precipitation of repeating sequences of phases in NiAl/Cu/Ni joints and the reliquation of the NiTi substrate in NiAl/Cu/NiTi bonds after the completion of isothermal solidification are examined.