The phase composition, structure and properties of composites based on the mechanical synthesizing powder alloys of Fe-B-C system.

The compact nanostructured composites based on the borocementite and ferrite were obtained using magnetic pulse compression (MPC) from the mechanical synthesizing powder alloys (Fe$_{83}$(C$_{1-X}$B$_X$)$_{17}$, Fe$_{75}$(C$_{1-X}$B$_X$)$_{25}$, Х = 0.2 and 0.4). The density of compacts after MPC was differed from 80 to 83 % of the theoretical density. The density increased with increasing the content of ferrite in alloys, the amount of ferrite depended on the total content of C and B, and the time of mechanical alloying. The sequence of phase and structural transformations was studied on the all steps of processing (mechanosynthesis, consolidation, sintering). It was shown that the powder alloys on the unfinished stage of mechanical alloying may be used to produce of the compacts. Further annealing at 800 $^{\circ}$C leads to the interaction of unreacted during mechanosynthesis phases and to the formation of the borocement and carboboride. In the compacts with Fe$_{83}$(C$_{1-X}$B$_X$)$_{17}$ composition retained about 18-26 vol. % of ferrite after sintering, their microhardness was 9.5-11.7 GPa. The compacts with Fe$_{75}$(C$_{1-X}$B$_X$)$_{25}$ composition contained only the carboboride phases, their microhardness ranged from 13.8 to 14.9 GPa. The compacts with composition Fe$_{83}$(C$_{1-X}$B$_X$)$_{17}$ and Fe$_{75}$(C$_{1-X}$B$_X$)$_{25}$ had similar abrasion resistance despite on the difference in the hardness.