Structure And Composition Of Cavitated Layers By Helium/Oxygen Plasma Based Ion Implantation On Titanium Alloy

Ti6Al4V alloy was treated by helium/oxygen plasma based ion implantation (He/O₂-PBII), surface treating– annealing, sputtering by argon ions and corrading, for Helium/oxygen implantation alloy samples. The effects of helium/oxygen implantation process parameters such as implantation voltage, implantation dose on the microstructure, micrograph and mechanics and friction behaviors were studied systematically.Helium bubbles and helium microcavities were formed by helium/oxygen plasma based ion implantation of Ti6Al4V alloy, helium bubbles and microcavities increase with the increasing of helium implantation dose, oxygen implantation restrains the increasing of helium by annealing. Annealing, argon ions sputtering and corroding are effective good methods for making helium bubbles in near alloy surface arriving at surface.In helium/oxygen implantation layer of Ti6Al4V alloy, on surface, the concentration of O are the highest, and the concentration of Ti are the lowest. In the sub surface layer, the O/Ti atomic ratio is 2. TiO₂ would be first formed around helium microcavities. Amorphous TiO₂ is the dominate phase in the implanted layer, and there is also rutile and brookite phase existing in the layers. The size of crystal grains in implanted layer is very small. Alloy annealed after helium/oxygen implantation at 500℃, there is no obviously phase transformation and there is no obviously phase growth in the implantation layer.The roughness of Ti6Al4V alloy surface declines by helium/oxygen ion implantation, but the roughness of helium implantation alloy increases after oxygen implantation. New structure TiO2 comes out in the implantation layer after annealing, smoothing the alloy surface, and decreasing the surface roughness.The nanohardness and modulous of Ti6Al4V alloy surface increase with the increasing of helium implantation energy, and decrease with the increasing of helium implantation dose. The friction coefficient of Ti6Al4V alloy surface declines with the helium/oxygen implantation dose. For the samples implanted at 10kV and 30kV with helium, the friction coefficients of alloy surface decline...