Artificial silicide barrier coatings in titanium matrix composites

Abstract

Abstract A continuous S2 silicide ([Ti,Zr] x Si y ) segregation layer was found in the fibre matrix interface of SCS6-SiC/Ti-5.8Al-4Sn-3.5Zr-0.7Nb-0.5Mo-0.35Si (IMI834) composites (composition in wt.%). The S2 layer separates completely the titanium matrix from the reaction layer. It was shown that the S2 layer stabilises the interface during thermal treatment. The thermal stability of composites was tested in which artificial coatings were introduced into the interface. For the artificial coatings a composition and structure of the S2 silicides were aspired. The interface of the composites was investigated with analytical transmission electron microscope in the as-processed condition and annealed at 700 °C for 3 000 h and at 800 °C for 1000 h. The coatings of the same composition and structure can be introduced into the interface of SiC-SCS6/IMI834 composites as those of the S2 silicide obtained by self-segregation. The composites with the artificial coatings have a similar interface stability at 700 °C as those obtained by self-segregation.