Selective laser melting of hypereutectic Al-Si40-powder using ultra-short laser pulses

We investigate the use of ultra-short laser pulses for the selective melting of Al-Si40-powder to fabricate complex light-weight structures with wall sizes below 100 μ m combined with higher tensile strength and lower thermal expansion coefficient in comparison to standard Al–Si alloys. During the cooling process using conventional techniques, large primary silicon particles are formed which impairs the mechanical and thermal properties. We demonstrate that these limitations can be overcome using ultra-short laser pulses enabling the rapid heating and cooling in a non-thermal equilibrium process. We analyze the morphology characteristics and micro-structures of single tracks and thin-walled structures depending on pulse energy, repetition rate and scanning velocity utilizing pulses with a duration of 500 fs at a wavelength of 1030 nm . The possibility to specifically change and optimize the microstructure is shown.