Influence of Friction Stir Processing on Novel Designed Aluminium-Based Alloy to Enhance Strength and Ductility

In the present study, a novel Al–Cu–Ni alloy was designed using ThermoCalc software, fabricated using vacuum arc melting and processed using friction stir processing (FSP). Scanning electron microscopy (SEM) attached with EDS was used to analyse the microstructural characteristics to identify the phases and the sequence in which they evolved during the solidification process. The SEM investigation shows that cast alloys contain eutectic and intermetallic phases of Al2Cu and Al7Cu4Ni. The thermal analysis also confirms the solidification path of the alloy, and a quasiperitectic reaction has been proposed. The influence of FSP on the mechanical behaviour of the cast Al-rich alloys was also examined in this study. The microstructural analysis revealed reduction in porosity after FSP as well as significant breakage and dissolution of the coarse eutectic and intermetallic phase dispersed at the grain boundaries, which significantly enhanced the tensile properties. After using FSP specimen, the ultimate tensile strength was increased to 334 MPa compared to 260 MPa and elongation % was increased to 11.6% compared to 4.3% in the as-cast Al-rich alloys. The Al7Cu4Ni phase particle size has been reduced to 0.83 ± 0.32 µm from 12.1 ± 2.7 µm. The results were discussed based on the microstructure characterization, phase analysis, and mechanical properties analysis.