Ion beam nitriding of titanium and titanium alloy

Titanium and Ti8Al1Mo1V alloy have been nitrided with an ion beam source of nitrogen or argon and nitrogen, at a total pressure of 2-10x10-4 torr. The treated surface has been characterized by surface profilometry, X-ray diffractometry, Auger Electron Spectroscopy (AES), and microhardness measurements. It was found that tetragonal Ti2N phase forms in pure titanium and Ti8Al2Mo1V alloy with traces of AlN in the alloy. Two opposite processes were found to compete during the ion beam nitriding: (a) formation of nitrides in the surface layers; (b) sputtering of the nitrided layers by the ion beam. The highest surface hardness, of about 500 kg mm-2 in titanium and 800 kg mm-2 in Ti8Al1Mo1V, was obtained by nitriding with an ion beam of pure nitrogen at 4.2x10-4 torr, at a beam voltage of 1000 V. (author)