The Mechanical Properties of the Novel Nanocrystalline Refractory Tantalum Alloys

The nanocrystalline tantalum alloys were investigated in terms of mechanical properties. The materials were obtained by powder metallurgy techniques-mechanical alloying (MA) and hot pressing (pulse plasma sintering mode). Pure powders of niobium, molybdenum, and tungsten were used for tantalum as an additive element in the concentration of 5, 10, 20, and 40 wt %. The analysis of XRD (Williamson-Hall equation) and TEM confirmed a significant reduction of the grain size (5.3-25.7 nm) for pure powders and (12.5-171.5 nm) for bulk hot-pressed elements. The nanoindentation test was used to study the mechanical properties. The load-displacement curves show high uniformity of the mechanical properties. The nanocrystalline alloys show very high hardness and stiffness. The highest value of hardness reached 1481 HV for Ta-10Mo composition. Significantly higher values of hardness compared to pure Ta-nano were measured for Ta-W system. The Young's modulus increased twice up to 343 GPa for Ta-20Mo in comparison to the unalloyed nanocrystalline Ta (163 GPa). In the novel nanocrystalline tantalum alloys, both solid solution and grain boundary strengthening affected on high mechanical properties.