Influence of annealing on mechanics behaviors of oxygen-implanted layer on Ti6Al4V by plasma-based ion implantation

Ti6Al4V was implanted by oxygen plasma based ion implantation at pulsed negative voltages of 50kV with a fluence of 4×1017 O/cm2. The implanting temperature of below 180°C was controlled by an oil cooling working table. Subsequent annealing was applied the implanted samples in vacuum at 600°C, 650°C and 700°C, respectively. The influence of annealing conditions on hardness and scratch resistance of the oxygen-implanted layer was investigated. The annealing at a lower temperature below 650°C makes the hardness peak widen and shift into the substrate. Scratch resistance of the oxygen implanted layer also was improved significantly. While the temperature increases to 650°C and 700°C, annealing induces a hardness valley value, which is even far lower than that of the substrate. At the same time, scratch resistance deteriorates for the oxygen implanted layer. All annealing samples have a higher elasticity recover than the implanted samples.