Experimental and numerical study of surface alloying by femtosecond laser radiation

Here we report on experimental studies of femtosecond laser induced surface metal alloying. We demonstrate that layers of different metals can be mixed in a certain range of laser pulse energies. Numeric simulations demonstrate that the sub-surface melting and mixing is advantaged through the difference in the electron-phonon coupling constants of the metals in the multi-layer system. Dependence of the depth of the mixed layer on the number of laser pulses per unit area is studied. Numeric simulations illustrate physical picture of the laser alloying process.

► We study femtosecond-laser induced metal alloying experimentally. ► We produce a sandwich-like structure by evaporating Au then Cu on glass substrate. ► XPS in-depth profiling reveals metal mixing on the Au/Cu interface after the laser alloying. ► Dependence of the mixed layer thickness on the processing parameters is studied.