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ABSTRACT An Al-Mg thin wall was fabricated using a Wire Arc Additive Manufacturing (WAAM) process, and then by applying Friction Stir Processing (FSP) in the presence of SiC nanoparticles, it was converted into a nanocomposite thin wall. The aim of this study was to engineer microstructural evolutions in Al-Mg/SiC nanocomposite thin walls. The main focus of this research was to investigate the relation between the bimodal grain structure in the stir zone (SZ) of the nanocomposite thin wall and the changes in mechanical properties, corrosion resistance, and wear resistance caused by increasing FSP passes. Although the dynamic recrystallization (DRX) mechanism during FSP, along with microstructural refinement, resulted in a fine-grained, equiaxed structure, the microstructure was not necessarily homogeneous. This heterogeneity in the SZ led to the non-uniform dispersion of nanoparticles. Further studies revealed that after three FSP passes, a uniform dispersion of SiC nanoparticles in the nanocomposite thin wall was achieved, contributing to a more uniform hardness distribution and an increase in hardness by approximately 187%. The ultimate tensile strength of around 345 MPa and an elongation to failure of 10% were obtained. In addition, the wear resistance of the nanocomposite thin wall improved by a factor of approximately 1.37, and the corrosion rate decreased by nearly 65%. The results showed that coarse grains in the bimodal grain structure, caused by the distinct material flows of the FSP tool, led to non-uniform nanoparticle dispersion. However, enhancing the role of the recrystallization mechanism in controlling the microstructure can improve this problem.
Badri et al. (Mon,) studied this question.