Mechanosynthesis of metastable cubic δ-Ta1−N

Mechanosynthesis of β-Cr2N using BN as the nitrogen source

“…It has been reported that the hardness of metal transition nitrides decreases with the increment of metal vacancies. For example, the hardness of δ-TaN, δ-Ta 0.82 N, and δ-Ta 0.67 N are 26 GPa, 18.2 Gpa, and 14.7 GPa, respectively [44]. Thus, although there are no similar reports regarding the β-Cr 2 N phase, from Fig.…”

“…The hardness of WC (22-28 GPa [1]) is higher than β-Cr 2 N (18.5 GPa [32]). However, some authors have shown that the particle size reduction (Hall-Petch effect) and decrease of metal vacancies increase the hardness of metallic nitrides [44,50,51]. Sanjin' es reported 27 GPa of microhardness and 22 GPa of nano hardness in β-Cr 2 N thin films deposited by magnetron sputtering [52].…”

“…Although the chromium nitrides and chromium borides do not show characteristic signals in the mid and near-infrared spectra [55][56][57], the h-BN does. The FTIR absorption spectrum of h-BN has distinctive bands at 1352 and 798 cm -1 corresponding to B-N bond stretching vibration and B-N-B out-of-plane bending vibration, respectively [44,57]. In Fig.…”

“…Therefore, the search for new methodologies is of great importance. High-energy ball-milling has proven to be a powerful technique for obtaining materials such as nitrides, carbides, borides, intermetallic and metastable phases [37][38][39][40][41][42][43][44]. Ball-milling has advantages such as easy operation, easy to scale industrially, short processing times, and that it could produce nanostructured powders.…”

“…Thus, the use of new nitrogen sources during mechanical milling could improve the synthesis of chromium nitrides. For example, Sun et al reduced the c-ZrN synthesis time using LiN as a nitrogen source [45], or Garcia-Mendoza et al demonstrated the formation of the metastable δ-TaN phase by a combination of high-energy ball-milling and the use of BN as nitrogen source [44].…”