Sintering of titanium and nickel nanopowders with a Nd: YAG nanosecond laser

Abstract

Experimental study on laser sintering of nanosized titanium and nickel powders using a nanosecond laser is reported in this paper. Pulse laser with a wavelength of 532 nm and pulse width (FWHM) of 23 nanoseconds is used. The diameters of the metal nanoparticles are between 35 to 50 nanometers. Pulse repetition rates range between 100 and 10,000 Hz and the average power is from 1 to 20 W. The powder bed is placed on a moving stage to control the scanning velocity. Sintered metal strips with 20 mm length are formed by focusing the laser beam on the surface of the moving power bed. Experiment results discover four different patterns of sintered metal strips. Nickel powder shows poor sintering ability due to severe shrinkage of the powder bed, while titanium powder forms solid sintered strips under specific parameters. However, scaly structure is observed in certain conditions which weakens the mechanical strength of the sintered strips.