Ion nitriding of titanium alpha plus beta alloy for fusion reactor applications

The titanium alpha plus beta alloy, Ti-6Al-4V, has been plasma nitrided at 1033 K in pure nitrogen to produce a 9 mu m thick surface nitride zone, followed by a 5 mu m thick Al-enriched zone and a 100 mu m thick nitrogen diffusion zone. X-ray diffraction and Auger electron spectroscopy indicate that the nitride zone consists of two layers: a thin TiN layer at the surface followed by a Ti2N layer, In preliminary tests, the deuterium retention of nitrided titanium specimens was determined after exposure to fluences of 4 x 10(25) m(-2), 60 eV D+ ions at 440 K and of 2 x 10(25) m(-2), 800 eV D+ ions at 623 K, The results are compared to the retention found for similar exposure of the untreated alloy and to model simulations. Implications for the use of these materials in a fusion environment are discussed. (C) 1998 Elsevier Science B.V.