High-temperature creep behaviors and microstructure characteristics of HIP-manufactured TiB/(TA15-Si) composites

This study investigated the creep behavior of hot isostatic pressing (HIP) manufactured 3.5 vol% TiB/(Ti-6.5Al-2Zr-Mo-V-0.3Si) composites. In-situ synthesized TiB whiskers and precipitated silicides were observed in the HIP-processed composite. To characterize its high-temperature performance, creep tests were conducted at 650 °C, 700 °C, and 750 °C at various applied stresses. The results revealed creep stress exponents of 4.79, 4.96, and 5.11 at 650 °C, 700 °C, and 750 °C, respectively. Corresponding threshold stresses were estimated as 31.5 MPa, 16.3 MPa, and 8.5 MPa. The post-creep microstructure was analyzed. It was found that creep cavities formed within the titanium matrix and at prior particle boundaries (PPBs) where TiB agglomerated, with creep rupture primarily occurring at the PPBs. Silicides coarsened during creep exposure, while smaller-sized silicides exhibited superior effectiveness in pinning dislocations. TiB whiskers acted as a skeleton, hindering the softening deformation of the TA15 matrix, and the fracture of TiB induced by dislocation pile-up was also observed.