激光辅助电弧增材制造 TiC/Al-Cu-Cd 合金组织性能研究

Objective To address critical issues such as coarse grain structure and excessive porosity inherent in high-strength Al-Cu alloys fabricated via wire arc additive manufacturing (WAAM), this study employs self-developed TiC/Al-Cu-Cd composite wires to systematically investigate the regulatory effects of both the laser-arc hybrid additive manufacturing (LAHAM) process and subsequent T6 heat treatment on the alloy microstructure and room-temperature tensile properties. The primary objective is to realize grain refinement, defect suppression, and the synergistic enhancement of strength and ductility, thereby providing a viable technical route for the high-quality additive manufacturing of high-strength aluminum alloys. Methods Single-wall components are fabricated via the LAHAM and WAAM processes, respectively (Fig. 1). Systematic comparative analyses of microstructural evolution, defect characteristics, and mechanical property discrepancies are conducted for as-deposited (AD) and T6 heat-treated (HT) components across the two processes. These analyses are performed using a suite of characterization and testing techniques, including an optical microscope (OM), a scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), electron backscatter diffraction (EBSD), microhardness measurements, and room-temperature tensile tests. Furthermore, a three-dimensional transient multiphase flow numerical model is developed, which couples fluid flow, heat transfer, and molten pool dynamics, to elucidate the underlying mechanism by which laser incorporation modulates molten pool behavior. Result and Discussions The as-deposited alloys fabricated via both processes are composed of equiaxed grains (Fig. 4). The incorporation of laser irradiation enables the formation of narrow, deep molten tracks in LAHAM-AD components. Combined with the results of numerical simulations, laser heating is shown to significantly enhance molten pool fluidity and facilitate gas escape, resulting in a substantial reduction in porosity for LAHAM-AD components relative to WAAM-AD components. Concurrently, the high-energy-density laser increases the cooling rate of the molten pool, which effectively inhibits grain growth and refines the average grain size: LAHAM-AD components exhibit an average grain size of (15.7±4.8)μm, compared to (23.1±7.5)μm for WAAM-AD components, corresponding to a grain refinement rate of 32%[Figs. 4(b) and (d)]. In the AD state, the elongation at break of the LAHAM-AD component reaches 9%, representing a 47.5% increase compared to that of the WAAM-AD component (6.1%), while its tensile strength is enhanced by 4% to 294.21 MPa (Fig. 10). After T6 heat treatment, the θ-Al_2Cu eutectic phases in components fabricated via both processes undergo extensive dissolution. For LAHAM-HT components, the tensile strength, yield strength, and microhardness reach 500.56 MPa, 473.66 MPa, and (160±3)HV, respectively—corresponding to increases of 7.3%, 17.3%, and 6.7% relative to those of WAAM-HT components. Fracture analysis reveals that LAHAM-AD components exhibit more uniformly distributed dimples without obvious secondary crack propagation, whereas LAHAM-HT components feature fine and dense dimples. Both fracture morphologies indicate superior strength-ductility synergy. Conclusions The LAHAM process effectively addresses the issues of coarse grain size and excessive porosity in TiC/Al-Cu-Cd alloys by coordinately regulating heat input, molten pool behavior, and solidification microstructure. When combined with T6 heat treatment, this process further promotes the dissolution of eutectic phases and the uniform precipitation of strengthening phases, thereby significantly optimizing the mechanical properties of the alloy. This study confirms the significant advantages of LAHAM technology in fabricating high-performance TiC/Al-Cu-Cd alloys, providing crucial technical support and a theoretical basis for the high-quality manufacturing of key load-bearing components in aerospace and other high-end fields.