Joining TiB2–TiC–SiC composite to Ta with a Ti/Ni/Ti interlayer: Interfacial microstructure and mechanical properties

Abstract

A TiB2–TiC–SiC composite was successfully joined to Ta by brazing with a Ti/Ni/Ti interlayer. The microstructure and properties of the Ta/TiB2–TiC–SiC joint were analyzed at various joining temperatures, and the reaction mechanism of the joint was studied. The results showed that α-Ti+(βTi, Ta) formed contiguous with the Ta substrate; the reaction layers of TiC, TiB, and (Ti, Ta)B formed adjacent to the TiB2–TiC–SiC composite, and Ti2Ni and (Ti, Ta)B formed in the central brazing seam. The reactions between the Ti and TiB2–TiC–SiC composite intensified as the joining temperature increased, and the reaction layer contiguous with the TiB2–TiC–SiC composite became thicker. The joint brazed at 1293 K for 20 min exhibited a maximum room temperature shear strength of 158 MPa, and the shear strengths at the high temperature of 873 K and 1073 K were 97 MPa and 74 MPa, respectively. The crack of the joint tested at room temperature was primarily propagated along the Ti2Ni phase of the brazing seam at 1253 K. When the joining temperature was relatively high, the fracture location changed to the TiB2–TiC–SiC composite. However, the fracture path of the joint that was tested at the high temperature of 1073 K occurred at the α-Ti+(βTi, Ta) phases.