Rapid in situ synthesis of bulk nanostructured titanium boride (TiB) ceramic, at the lowest possible processing temperature, is demonstrated. Using electric-field-activated-sintering (EFAS), nanoscale TiB whiskers were formed and densified uniformly throughout the volume, from a mixture of micron-sized Ti, TiB 2 and FeMo powders, at 1100°C in 30 min and at a relatively low pressure. Microstructure and X-ray diffraction (XRD) analysis, revealing the formation of TiB whiskers in this rapid processing condition, are presented. The formation of a transitional quaternary liquid phase, facilitated by localized joule heating at particle contacts, are hypothesized as contributors to rapid and low-temperature synthesis.The prospect of achieving a dense, refined microstructure in ceramics during sintering, at the lowest possible temperature, is not only scientifically intriguing but also practically very important in the context of reducing the time and the cost of manufacturing. In this context, the electric-field-activated-sintering (EFAS) process has emerged as a promising approach, for ceramics [1,2], cermets [3,4], and metal matrix composites [5,6]. With EFAS, there is potential to reduce the sintering temperature and time because of the generation of high rates of heat by the passage of electrical current through the conductive powders, which can accelerate local heating and diffusion, reaction, and sintering. A combination of these processes, which depends on the ceramic, can lead to rapid densification with a very fine grain size and a uniform microstructure. An open question, however, is whether the relevant chemical reaction, especially in the context of reaction sintering of ceramics, will be completed, and the ceramic will be densified, in the relatively shorter processing time.Titanium boride (TiB) is a new, hard, nano-ceramic material that was previously synthesized in our group [7,8,9] by hot-pressing of constituent powders. The major attractive feature of this boride ceramic is its dense, highly compact, and three-dimensional network of nanostructured TiB whiskers, which gives the ceramic the bulk form. This ceramic has been shown to have a very attractive set of mechanical properties: relatively high values of hardness (~1600-1800 kg/mm 2 ) [10], Young's modulus (~427 GPa) [11], flexure strength (~850 MPa)[10], fracture toughness (5.2 MPa √m), and, excellent wear resistance against Si 3 N 4 [12]. These properties are quite compelling and mark the excellent potential for engineering applications. Our previous work, however, was based on hot-pressed samples (75 × 75 × 12.7 mm) of bulk nanostructured TiB. However, for complete reactive formation and densification of TiB in hot pressing, a temperature of at least 1350°C and a period of 2 h, at a pressure of 15-20 MPa, were required.In this report, we demonstrate the first synthesis of bulk nanostructured TiB, at the lowest possible temperature (1100°C) and in a relatively short time (~30 min.), which resulted in uniform reaction and formation of TiB whiskers a...
