Structure and Mechanical Behavior of Al–Nb Hybrids Obtained by High‐Pressure‐Torsion‐Induced Diffusion Bonding and Subsequent Annealing

Abstract

The main approach of mechanical consolidation of dissimilar metals consists in solid state joining of thin discs or powders by means of pressure‐assisted shear deformation. Prior to this research, most strongly dissimilar systems, such as Al–W and Al–Ti, were only bonded by means of mechanical alloying and subsequent powder compaction. Herein, pioneering experimental research on the one‐step synthesis of an Al–Nb composite by means of diffusion bonding through high‐pressure torsion that allows figuring out several unusual results is presented. The maximal microhardness value is revealed to locate in the middle radius area, decreasing at the sample edge. Formation of a small amount of Al3Nb intermetallic phase is detected at room temperature deformation, while its equilibrium formation normally occurs above 600 °C. Post‐deformational annealing at 400 °C results in the overall decrease of the microhardness value along with its growth on the sample edge. Annealing at 600 °C does not lead to any degradation of the mechanical characteristics by comparison to those after annealing at 400 °C. The obtained results are discussed and explained in frames of contribution of different factors to the strengthening and softening dynamics of the composite material.