Nanocrystalline phase formation and surface smoothing of titanium by intense pulsed ion beam irradiations

Abstract

Summary form only given. Metal surface characterization by irradiation of an intense pulsed ion beam (IPIB) has been studied experimentally. The IPIB irradiation of metals leads to rapid heating of the surface which is immediately followed by rapid cooling and resolidification, resulting in metal surface modification. Attention is focused on the formation of nanocrystalline phase and the reduction of machining roughness on a titanium surface. The experiments were performed with the pulse power generator HARIMA-II (400 kV, 3/spl Omega/ and 50 ns) at the Himeji Institute of Technology. The IPIB was produced by an inverse pinch ion diode with a ring anode of 50 mm diameter and an annular cathode projected from a circular plate of 16 mm diameter. Using the Teflon plate as an ion source, the power density and pulse width of IPIB were 34 MW/cm/sup 2/ and 30 ns, respectively. The dominant ion species were found to be the carbon (53%) and the fluorine (47%) by a Thomson-Parabola ion spectrometer. Using the acrylic plate as an ion source, the power density and pulse width of IPIB were 70 MW/cm/sup 2/ and 50 ns, respectively. The most dominant ion species was found to be hydrogen. The formation of nanostructured titanium by IPIB-irradiation is successfully demonstrated. The X-ray diffraction peaks of IPIB-irradiated titanium are broadened compared with that of non-irradiated titanium. The grain size of IPIB-irradiated titanium is estimated to be approximately 11 nm using Scherrer's formula. The reduction of machining roughness on the titanium surface was also realized by IPIB-irradiation.