An approach for fabrication of Al-Cu composite by high pressure torsion

Abstract The method utilizing high-pressure torsion (HPT) processing followed by annealing to fabricate Cu-Al in situ composite with enhanced mechanical properties is presented. The initial sample consists of three metal discs Cu/Al/Cu was processed by HPT (5 GPa, 5 turns). The analyses of the microstructure after HPT carried out by transmission electron microscopy and scanning electron microscopy equipped with energy dispersive spectrometry (EDS). After HPT, the development of nanostructure with the mean crystallite size of about 100 nm in the produced sample was revealed with the small presence of the intermetallic phases. Investigation of the kinetics during subsequent annealing at 450 °C/30 min showed the in situ formation of intermetallic Al2Cu, AlCu, Al3Cu4, Al2Cu3 and Al4Cu9 phases in the copper matrix which was detected by EDS. The formation of intermetallic phases after annealing was also confirmed by X-ray diffraction. The results showed that microhardness of the composite considerably increases from an initial value of ∼ 380 for HPT sample to a saturation value of ∼ 900 after annealing.