Effect Of Annealing On Microstructures And Mechanical Properties Of Ultra-fine Grained Pure Cu,Pure Al And Cu/Al Laminated Composites Processed By Accumulative Roll-bonding (ARB)

Annealing behavior of UFG copper and UFG Al was analyst.1、3 and 6 passes of ultrafine grained pure copper and pure Al plates were fabricated by accumulative roll bonding. Cu samples were processed on different temperature with different minutes, and the mechanical properties were studied. SEM was used to investigate the microstructure evolution of annealed Cu. Heat treatment was induced in Al samples on 300℃, and tensile strength and micro-hardness was tested. TEM technology was used to learn the microstructure evolution of 6 cycles annealed Al samples. Microstructure and mechanical properties of high strength Al-Cu composite sheets prepared by ARB and intermediate annealing (IA) were studied. Al-Cu composite plates were prepared by 2 cycles cold rolling plus annealing of 30 min on 350℃. Post annealing was installed on 6 cycles IA samples. Intermediate phase evolution law was studied by XRD technology.The results show that mechanical strength and hardness of ultrafine grained copper and Al plates are decreased with the increasing of anneal time. With the passes of ARB increasing, thermal stability of ultrafine grained copper and Al both become worse. Hardening layers was introduced near the interface during sample surface processing. Thermal stability of hardening layer is higher than that of the substrat. The reason may be that hardening layer contains lamellar nanocrystal and large amount of deformation twins.It is found that tensile strength of 6 passes CR Al/Cu is about 310 MPa, while tensile strength of the same passes of IA is 372 MPa. The strength of IA increases by 20% compared with the former. Al2Cu and Al4Cu9 phases were generated at the interface of 6 passes after annealing. Mechanical property shows that thermal stability of samples processed by IA is better than that of CR. The analysis suggests that intermediate annealing can effectively promote atomic diffusion and boosting at the interface of Al and Cu layer. At the same time, another effect of intermediate annealing is that the decrement of difference of rheological stress between Cu layers and Al layers can delay Cu layer neck. This may be a reason why samples fabricated by IA have better thermal stability.