Ultra-hard, multi-phase nanocrystalline MoTa and MoTaTi based concentrated refractory alloys

摘要

? 2022 Elsevier B.V.Binary (MoTa) and ternary (MoTaTi) based concentrated refractory alloys are synthesized using ball milling and spark plasma sintering. A single BCC phase which was observed after high energy ball milling has transformed to multiple phases after sintering. Presence of Ti and Fe (from milling media) appears to trigger the phase transformations. An extremely high hardness in the range 16–10 GPa was measured in the load range 0.25–9.81 N and with a very distinct indentation size effect. Density-normalized hardness was found to be exceptionally high indicating their potential for high strength/density applications. This study also suggests that several elements need not be added in high concentrations to achieve high end mechanical properties.