Reducing sensitivity of mechanical properties to assembly gap size in AA5083/TA5 dissimilar joints via a transverse alternating magnetic field in laser fusion brazing process

Abstract

The achievement of high-quality AA5083/TA5 dissimilar butt joints via laser fusion brazing remains challenging due to the high sensitivity of microstructure and mechanical properties to process parameters. This study explores the effectiveness of a transverse alternating magnetic field (AMF) in reducing the adverse effects of assembly gap size on weld appearance, microstructure and mechanical properties of AA5083/TA5 laser fusion brazed butt joints. The results demonstrate that the magnetic field supports the molten pool and enhances wetting of aluminum alloy on the titanium plate. The stirring effect homogenizes the temperature field within the molten pool, resulting in an I-shaped transformation of aluminum weld and reduced angular deformation. Moreover, by generating a thermal electromagnetic force up to 10⁵ Nm⁻³ at the solidification interface, the alternating magnetic field breaks up large-sized dendrites and alters grain growth direction for both aluminum dendrites and TiAl₃ grains. Consequently, it increases dispersed heterogeneous nucleation TiAl₃ particles content within aluminum welds while refining their grain structure. Furthermore, this refinement inhibits the severe hot cracks in N_0.3 joint through synergistic effects with texture optimization. The mitigated nanomechanical property mismatches at phase interface strengthens the TiAl₃ interface. The tensile strength of joints decreases slightly from 280.75 MPa for W_0 joint to 268.48 MPa for W_0.3 joint, comparable to the N0 joint. This study demonstrates a promising approach for reducing the sensitivity of microstructure and mechanical properties to process parameters by applying a magnetic field during Al/Ti laser fusion brazing process.