Effect of Friction Stir Processing on Microstructure and Mechanical Properties of In-Situ Composite A356/Al3Ni Fabricated by Stir Casting

A new technique for refining grains and creating surface composite materials was created using friction stir processing (FSP), which shows promise for improving the properties of metals. This technology can effectively overcome the limitations of methods that depend on melting. The work employed stir casting to produce in-situ composites, including an Al₃Ni reinforcing phase, Al alloy A356, and 15% weight percent pure Ni powder. The development of several phases of Al₃Ni, AlNi, and Al₃Ni₂, which are dispersed throughout the matrix of A356 alloy, was verified by XRD analytical examination. The objective was to determine how FSP impacted the stir-cast A356/Al3Ni in-situ composite's mechanical properties and microstructure. Porosity was successfully reduced, the α-Al dendrites were refined, the main Si phase and Al₃Ni were broken and fragmented, and the grain structure was improved by the FSP method. There was a consistent and equal distribution of in-situ Al₃Ni in the stir zone (SZ). There were no hazardous phases present when the particle and matrix came into contact. The application of FSP improved the tensile strength of the A356 alloy by 38.35% and the in-situ composite A356/Al₃Ni by 69.17%. It was found that the improvement in hardness was 14.47% for A356 alloy after FSP and 13.81% for in-situ composite A356/Al₃Ni compared to in-situ composite without FSP.