Magnetic Response of Arc-Melted and Fire-Melted Beads on Copper Wires

초록

Distinguishing arc-melted from fire-melted beads on copper wires is important for interpreting electrical causation in fire investigations. Magnetization measurements were applied as a non-destructive method for characterizing the magnetic behavior of the two bead types at room temperature. Arc-melted beads exhibited paramagnetic behavior, whereas fire-melted beads showed predominantly diamagnetic behavior. This contrast is interpreted in relation to the oxide phases formed under different oxygen environments, where CuO is favored in oxygen-rich conditions and Cu2O becomes relatively more favorable in oxygen-deficient conditions. The absence of hysteresis with no ferromagnetic contaminants in the energy-dispersive spectroscopy results confirms that the paramagnetic signal in arc-melted beads is intrinsic to the CuO-containing oxide. Arc-melted beads also showed weak magnetic anisotropy, whereas fire-melted beads showed isotropic behavior. These results suggest that non-destructive magnetization measurements may serve as a useful preliminary screening method for bead discrimination, preserving the specimen for subsequent analysis.

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