Effect of ECAP on Mechanical Properties and Corrosion Resistance of 2024-CNTs@Ni Composite

The 2024-1.5 wt%CNTs@Ni (Nickel-coated carbon nanotubes) composite were subjected to equal channel angle pressing (ECAP) deformation treatment and the microstructure, hardness distribution and tensile properties were investigated and discussed. The quasi-in-situ corrosion observation and COMSOL corrosion simulation were used to analyze and reveal its corrosion behavior. The results showed that the stress and microstrain are mainly concentrated in the area near the inside corner, and the closer the inside corner, the finer the grain size and the more dispersed the second phase and CNTs@Ni. The average hardness of the ECAP-treated composite was about 136.54 HV, which was 44.41% higher than that of the as-cast composite (94.55 HV). The properties of the ECAP-treated composite were all higher than the as-cast composite, with the yield strength, tensile strength and elongation increasing to 283.49 MPa, 399.18 MPa and 11.69%, respectively, which were about 44.99%, 45.97% and 344.49% higher than the as-cast composite. The electrochemical properties of the ECAP-treated composite were better than the as-cast composite, with a corrosion current density of 88.319 μA∙cm², which was 12.33% lower than that of the as-cast composite. The COMSOL simulation results indicated that the ECAP-treated composite required a longer time when the electrolyte was immersed to the same depth.