Severe plastic deformation of two-phase TiNiCuNb shape memory alloy

•Two-phase TiNiCuNb alloy was subjected to HPT process.•Nanocrystalline bands alternating with amorphous phase after HPT.•Nanoscale debris are embedded into amorphous phase. (Ti54Ni34Cu12)90Nb10 alloy with initial two-phase structure of B19 martensite and β-Nb phase was subjected to high-pressure torsion (HPT) process at room temperature. HPT leads to the formation of nanocrystalline bands of β-Nb phase alternating with amorphous matrix. Nanocrystalline debris of B2 phase was found to be embedded into the amorphous matrix. Refinement of β-Nb phase upon HPT is much greater compared to that for pure Nb alloy.