Gradient grain distribution and enhanced properties of novel laminated Ti-TiBw/Ti composites by reaction hot-pressing

A novel laminated Ti-TiBw/Ti composite containing Ti layers and TiBw/Ti composite layers were successfully fabricated by the reaction hot-pressing technique. The TiB whiskers and their network distribution structure play an effective role in microstructural evolution of the Ti matrix during the sintering and cooling processes. Interestingly, the morphology and size of grains in the laminated Ti-TiBw/Ti composites exhibit gradient distribution. The Ti layer comprises coarse lath-like grains while the TiBw/Ti composite layer contains two different sizes of equiaxed grains. A combination of high strength and ductility can be obtained by incorporating a low volume fraction of in-situ TiBw through the grain refinement mechanism and the laminated structure. The TiBw/Ti composite layer with high strain hardening rate delays localized necking of the Ti layer. The novel laminated structure of Ti-TiBw/Ti composite allocates stress and strain reasonably well and reveals a prolonged uniform plastic deformation capability.