Deformation twinning and localized amorphization in nanocrystalline tantalum induced by sliding friction

•Nanostructured Ta with extremely small grains of less than 10 nm was fabricated.•Deformation twins and amorphous boundaries were observed in nanocrystalline Ta.•Deformation twinning and amorphization are the possible deformation mechanisms.

We reported the formation of nanocrystalline structure in the surface layer of a pure tantalum plate under sliding friction treatment. Nanocrystalline grains of 7 nm with amorphous boundaries were formed in the topmost surface layer of Ta plate. Deformation twins were also observed in the nanocrystalline grains with size below 20 nm. Deformation twinning and localized amorphization are the possible deformation mechanisms in the top surface layer of tantalum induced by sliding friction.