Temperature and wavelength-dependent spectral absorptivities of metallic materials in the infrared

The optical constants and absorptivity of selected elemental metals and alloys are calculated based on the Drude-type model. The calculations are made primarily at the CO2 (10.6-mu m) and the Nd:YAG (1.06-mu m) laser wavelengths, with consideration for laser material processing. The absorptivities at these wavelengths are calculated for some important metallic materials. For the application of laser material processing, temperature-dependent values are calculated based on available experimental data. The absorptivity values for alloys are calculated by assuming that the sum of contributions of the proportionality of the valence electrons to the effective mass of an electron for each constituent metal is equal to the proportionality of the valence electrons to the effective mass of an electron for the alloy. The absorptivities of the elemental metals at 10.6 mu m agreed with experimental data very well, except for transition metals. Agreement of alloy and element absorptivity calculated values and experimental data is good at 10.6 mu m but not at 1.06 mu m. Overall the calculation by the Drude model gives good estimates of absorptivity at 10.6 mu m.