Microstructure, microhardness and work function of in-situ Al-Cu composite processed by mechanical alloying by means of high-pressure torsion.

Mechanical alloying of dissimilar metals employing the severe plastic deformation techniques established itself to be a perspective method of obtaining in situ metal matrix composites with advanced properties. Recent investigations in this field discovered that besides severe mixing of elements, intensive formation of non-equilibrium intermetallic phases takes place. The presence of intermetallic particles in the composite affects both its physical and mechanical properties. In this work, we have realized the consolidation of Al–Cu composites by means of high-pressure torsion (HPT) technique. A non-trivial phenomenon of annealing-induced growth of microhardness was revealed. It was explained by the precipitation of intermetallic phases in the vicinity of Al–Cu interphases. The microstructural observations and X-ray diffraction analysis identified the set of the intermetallic phases present in the deformed composite. Formation of Al 2 Cu and Al 4 Cu 9 phases was observed. It is a well-known fact that the phase composition of the material has a strong impact on both electronic and mechanical properties being dependent on both the interatomic bonding nature and strength. In this work, using the density functional theory approach, we have calculated the work function (WF) values of intermetallic phases and compared them to the experimentally measured WF values of the metal matrix composite. Comparison of results allowed us to conclude that they demonstrate a fair coincidence. Due to the fact that the quantitative and qualitative composition of the intermetallic phases in the composite can be controlled using thermomechanical treatment modes, this approach can be considered as a way to control the WF value of the material. And after establishing the correlation of electronic and mechanical properties, a definite metal-matrix composites (MMC) can be treated as an approach for creation the composite with tailorable complex of physical and mechanical properties. [ABSTRACT FROM AUTHOR]