In-situ manipulation of TiB whisker orientation and investigation of its high-temperature mechanical properties in titanium matrix composites

Abstract

“SPS pre-sintering + SPS reactive hot extrusion” (SPSHE) is a promising technique for manipulating the orientation of TiB whiskers (TiBw) in discontinuously reinforced titanium matrix composites (DRTMCs). In the current study, (12.4 vol % TiBw +2.9 vol % TiC)/Ti6Al4V composites were prepared using SPSHE technology, successfully achieving both the normalization of TiBw orientation and a high aspect ratio. Specifically, the [010] axis of TiBw was aligned with the extrusion direction, and the average aspect ratio was 24.86. Tensile tests were conducted on the DRTMC samples at temperatures of 873 K, 923 K, and 973 K. The results demonstrate that SPSHE significantly enhances the high-temperature strength of the composite. At 873 K, the DRTMC exhibited an exceptionally high tensile strength of 732.2 ± 20 MPa. The main strengthening mechanisms of the DRTMC include load transfer strengthening from TiBw and TiC particles, solution strengthening, fine grain strengthening and dislocation strengthening. Moreover, at 873 K and 923 K, the dominant failure mode of the reinforcement was a load-bearing fracture. However, as the test temperature increased to 973 K, a mixed failure mode of load-bearing fracture and interface debonding was observed in the reinforcement.