Optimization of microstructure and properties of high-silicon aluminum alloys for electronic packaging based on semi-solid thixotropic forming process

Abstract

This study utilizes a semi-solid thixotropic forming strategy to achieve plastic deformation of Al–50Si alloy, optimizing its microstructure and properties. Various techniques, including large-area EBSD stitching, SEM, nanoindentation, and hardness testing, are used to investigate the alloy's recrystallization behavior, texture evolution, and stress distribution. The results highlight the mechanisms responsible for the microstructural changes and the enhancement of mechanical properties. Following thixotropic forming, the coarse Si phases within the alloy are fragmented. The average size of the primary Si particles decreases from 122.88 μm to 17.33 μm, a reduction of 85.90 %. Due to the synergistic effects of multiple mechanisms during forming process, the alloy's hardness increases from 81.29 HV to 155.83 HV, a 91.70 % improvement. The effectiveness of the strengthening strategy is further confirmed through ROM and Turner model analyses. Overall, this study demonstrates the feasibility of applying semi-solid forming techniques to fabricate Al–50Si materials. Not only does this approach expand the processing window for high-silicon aluminum alloys, but it also offers new insights into optimizing the microstructure and properties of difficult-to-deform materials.