Phase transformation mechanism of Ti/Ti ₅ Si ₃ dual-phase targets via ball milling modification and SPS

Commercial TiSi targets typically consist of coexisting Ti, TiSi 2 , and Ti 5 Si 3 phases, inducing severe differential etching and elemental segregation during sputtering. This causes compositional inhomogeneity and poor service stability of deposited TiSiN coatings, limiting their large-scale application under extreme operating conditions. To address this industrial bottleneck, this work employs TiH 2 powder to replace conventional high-purity Ti powder. By coupling ball milling modification with the intrinsic dehydrogenation of TiH 2 , homogeneous Ti-Si targets with a dual-phase Ti/Ti 5 Si 3 structure are fabricated via spark plasma sintering (SPS). The effects of ball milling on the microstructure and dehydrogenation behavior of TiH 2 -TiSi 2 mixed powders, as well as subsequent sintering densification and phase evolution, are systematically investigated, and the coupling mechanism among dehydrogenation, densification, and phase transformation is elucidated. The optimised ball milling process refines the volume-based median particle size Dv(50) to 0.306 μm and achieves complete TiSi 2 -to-Ti 5 Si 3 phase transformation at 700°C. The as-prepared target reaches a relative density of 99.87%, with uniformly dispersed Ti and Si elements whose atomic ratio matches the designed Ti:Si = 75:25, and a Vickers hardness exceeding 1000 HV. This work provides a reliable technical route and theoretical support for the low-cost fabrication of highly homogeneous Ti-Si targets, with important engineering implications for improving the service stability of TiSiN coatings.