<p>Vacuum brazing of graphite/tungsten (W) and graphite/316 stainless steel (316SS) joints was conducted using Ag–Cu–In–Ti filler alloy at 800&#xa0;°C. Microstructural analysis revealed that defect-free interfacial bonding was achieved between the substrates and filler zone, and a TiC reaction layer was formed at the graphite/filler zone interface for both joints. For the graphite/W joint, the filler zone was mainly composed of Ag solid solution (ss), Cu(ss), Cu₇In₃, and Ti–Cu intermetallic compounds (IMCs). No detectable interfacial reaction, diffusion or dissolution occurred at the W/filler zone interface, and the reliable bonding was mainly attributed to the preferential adsorption of active Ti on the W surface. For the graphite/316SS joint, the filler zone was mainly composed of Ag(ss), Cu(ss), as well as Ti–Cu, Cu–In and Ni–Ti IMCs. In addition, interdiffusion occurred between 316SS substrate and the molten filler, forming a diffusion zone at the 316SS/filler zone interface, which was mainly composed of Fe₂Ti and σ–(Fe, Cr) phases. The nanoindentation results of the joint zones were consistent with the identified phase constitutions. The average shear strength of the graphite/W and graphite/316SS joints reached 73.0% and 95.7% of the graphite substrate strength, respectively. All joints fractured in the graphite substrate adjacent to the filler zone after shear tests, indicating that high residual thermal stress was concentrated at the graphite side induced by the thermal expansion mismatch between graphite and filler alloy.</p>