1：Experimental Design and Method Selection:

The study uses quasi-continuous wave (QCW) and continuous wave (CW) laser surface melting (LSM) to treat 2219 aluminium alloy samples, comparing with as-received samples. The rationale is to leverage the fast cooling rate and multi-directional solidification of QCW-LSM to refine microstructure and reduce solute segregation.

2：Sample Selection and Data Sources:

The material is a homogenized ingot of 2219 Al-Cu alloy, with compositions measured by inductively coupled plasma optical emission spectrometry. Samples are polished and cleaned before laser treatment.

3：List of Experimental Equipment and Materials:

Equipment includes an Yb-fiber laser (IPG YLS-5000), scanning electron microscopy (SEM, JSM-5600LV, JEOL), electron probe microanalysis (EPMA, JXA-8230), X-ray diffraction (XRD), scanning Kelvin probe force microscopy (SKPFM, Bruker Multimode 8), X-ray photoelectron spectroscopy (XPS, Thermo Fisher), and a Zennium potentiostat for electrochemical tests. Materials include 2219 aluminium alloy, argon gas for inert environment, and 3.5% NaCl solution for corrosion tests.

4：5% NaCl solution for corrosion tests. Experimental Procedures and Operational Workflow:

4. Experimental Procedures and Operational Workflow: Laser treatments are performed in CW and QCW modes with specific parameters (e.g., power, scanning velocity, overlap ratio). Metallurgical and compositional analyses are conducted using SEM, EPMA, XRD, SKPFM, and XPS. Corrosion evaluations include cyclic potentiodynamic polarization tests and immersion tests in NaCl solution, followed by morphological and compositional analyses.

5：Data Analysis Methods:

Morphological parameters of Cu-rich precipitates are quantified using circle equivalent diameter, shape factor, and area fraction. Electrochemical data are analyzed for corrosion potential, pitting potential, and current densities. Statistical analysis is applied to EPMA and SKPFM data.