Tensile and creep properties of diffusion bonded titanium alloy IMI 834 to gamma titanium aluminide IHI Alloy 01A

Abstract

Diffusion bonding of the Ti-alloy Ti–5.8Al–4.0Sn–3.5Zr–0.7Nb–0.5Mo–0.35Si–0.06C (wt%) to the intermetallic γ-based alloy Ti–33Al–2Fe–1.8V–0.1B (wt%) using hot isostatic pressing at 900°C, 200 MPa held for 1 h was studied. Sound joints without any pores or cracks with a width of approximately 5–7 μm could be produced. Tensile testing showed that the strengths of the joints are similar to the strength of the γ-TiAl base material at temperatures between room temperature and 600°C. The fracture occurs either at the joint or in the γ-TiAl material. The fracture initiation process is a competition between initiation in the γ-TiAl base material and initiation at the γ-TiAl/diffusion bond interface. Creep testing showed that most of the creep elongation occurs in the Ti-alloy, but failure is initiated in the joint bond line. Creep causes degradation and pore formation in this line. Interlinkage of these pores creates a crack which grows slowly until the fracture toughness of the γ-TiAl is exceeded and the crack starts to propagate in the γ-TiAl material and terminates creep life.