[en] The methods of radiography of crystalline grains isolated from annealed (1170 K) alloys are used to study a low temperature modification of Nb₂C (βsub(r)-Nb₂C) with rhombically distorted structure as against high-temperature HCP-phase (β). It is shown that the βsub(r)-phase in the frames of an elementary cell of the metal atom lattice is hereditary-oriented relative to the initial β-phase in compliance with the correlation. Actual sizes of superstructural rhombic elementary cell βsub(r)-Nb₂C are determined for the first time