Joining of Nanostructured Ferritic 14YWT Alloys by Spark Plasma Technique

Spark plasma joining of nanostructured ferritic 14YWT alloys has been carried out at 800°C, 1020 °C and 1030 °C in vacuum. The characteristics of joining as a function of temperatures were investigated using bulk density, nanoindentation and electron backscattered diffraction techniques. Joining performed at 1020 °C and 1030 °C shows a complete, uniform bonding of the samples, whereas the samples joined at 800 °C showed a visible crack that runs along the entire sample length. Bulk density measurements indicate that the reduction in density of samples joined at 800 °C is due to the presence of voids at the interface. The presence of columnar grains only close to the interface at 800 °C suggests the possibility of a steep temperature rise locally at the interface that is attributed to high electrical contact resistance at the interface.