Mechanical properties of nanocrystalline TiC–ZrC solid solutions fabricated by spark plasma sintering

Phase decomposition of TiC−ZrC solid solution prepared by spark plasma sintering

“…Conversely, the toughness of ceramic materials may decrease as grain size decreases because of the reduction in the number of obstacles for crack propagation [22,23]. Liu et al reported grain size refinement of Ti x Zr 1À x C 1À δ solid solutions with various x values by SPS; the hardness increased with increasing the x value and exhibited a maximum of 24 GPa at x=0.7, whereas the toughness showed an opposite dependence on the x value and was minimized at x=0.7 [9]. In this study, the hardness and toughness of the 90TiCÀ 10ZrC composite were simultaneously reinforced by the heat treatment that assembled the nodular structures with sizes of several tens and hundreds of nanometers.…”

“…Although spark plasma sintering (SPS) is often employed to consolidate refractory carbides, monolithic fully dense ZrC and TiC bodies are difficult to obtain [2,8,9]. The TiC À ZrC system is a complete solid solution system, and we have demonstrated that 10 mol% ZrC can significantly enhance the sinterability of TiC À ZrC composites by forming homogeneous solid solutions [10,11].…”

“…TiC À ZrC nanocomposites were fabricated by the combination of mechanical alloying and SPS using Ti, Zr and carbon black powders [8,9]; these nanocomposites had a Vickers hardness (H V ) of 24 GPa and fracture toughness (K IC ) of 6.9 MPa m 1/2 [9]. Knotek and Barimani reported that TiC À ZrC thin films prepared by sputtering and heat treatment at 1273 K caused precipitation of a TiC-rich solid solution with dimensions of several tens of nanometers in a matrix of the ZrC-rich solid solution [16].…”

Microstructure and mechanical properties of hot-pressed ZrC–Ti–CNTs composites

“…, which was given by Mendelson [27]. As a result, a small grain size of 1.2 μm was obtained, which could be attributed to the ability of grain size refinements of the formed (Zr,Ti)C solid solution [16]. Moreover, the secondary cracks caused by crack branching were found in the fracture surface of ZTC, as marked by arrows in Fig.…”

“…Similarly, the shifts of ZrC peak positions were also found by other authors. They attributed this to the formation of solid solution, which could change the crystal lattice size and cause shift of diffraction peak positions [16,19]. It is generally known that both ZrC and TiC belong to the cubic crystal structure of NaCl-type.…”