Integrated SPA-L, Mechanical, and Antibacterial Evaluation of High-Purity Aluminum: Linking Plasma Signatures to Alloy Performance

This paper describes a diagnostic investigation of aluminum plasma for simultaneously evaluating the spectral and mechanical characteristics of a high-purity Al alloys. A Stimulated Plasma Analysis by Laser (SPA-L) system based on a pulsed Nd:YAG laser was created to produce and study plasma in air. The Distinct Spectral Plasma Sign (DSPS) and Curve Fitting Solution revealed twelve strong analytical Al lines (AL1-AL12), which were then utilized to determine plasma parameters and elemental concentrations. The plasma temperature and electron density were determined to be tP=7586.9°C and ρ≈8.83×1012 cm−3, with a very low average relative divergence from NIST wavelengths (≈1.35×10−4), validating the diagnostics\' trustworthiness. Quantitative SPA-L analysis confirmed aluminum as the primary element (~97.6 wt.%), with total petty impurity and trace additions of 2.166, 0.1899, and 0.0139 wt.%, respectively. This revealed several minor elements that were not discovered by XRF, which only recognized Al, Fe, Si, and Mg. XRD verified a single-phase FCC Al matrix. AFM revealed homogenous nanoscale surface roughness. Tensile studies on three alloy classes (X1-X3) at room temperature and 125°C revealed that minor-element composition changes had a considerable effect on yield strength, ultimate tensile strength, and strain hardening, with strength decreasing as temperature increases.\r\nAntibacterial activity tests against Escherichia coli, Acinetobacter baumannii, Staphylococcus aureus, Staphylococcus citrus, and Streptococcus faecalis revealed inhibition zones of only 8-9 mm, equivalent to the well diameter, indicating that the treated surfaces had no significant antibacterial effect under the tested conditions. The findings reveal that SPA-L is a sensitive, fast, and basically non-destructive method for connecting plasma diagnostics, alloy chemistry, and mechanical performance in a high-purity Al alloys aluminum conductors.\r\n