Structure of Surface-Modified Layers of Calcium-Ion-Implanted Ti–6Al–4V and Ti–56Ni

The structures of surface-modified layers of calcium-ion (Ca2+)-implanted Ti-6 mass%Al-4 mass%V and Ti-56 mass%Ni were characterized using Auger electron spectroscopy with argon-ion-sputtering and X-ray photoelectron spectroscopy. Calcium ions were implanted in Ti–6Al–4V and Ti–56Ni in the amount of 1022 ions/m2 with an acceleration energy of 2.88 fJ (18 keV). The surface oxide layers of these alloys grew to approximately 12 nm as a result of the Ca2+-implantation. The oxide layers contained hydroxide. The outermost layer of the surface oxide was 3-nm-thick calcium oxy-hydroxide. A large part of the surface-modified layer, existing inside the calcium oxide, consisted of a mixture of titanium oxide, aluminum oxide and calcium oxide in Ca2+-implanted Ti–6Al–4V, and a mixture of titanium oxide, nickel oxide and calcium oxide in Ca2+-implanted Ti–56Ni. In Ca2+-implanted Ti–6Al–4V, Ca2+-free oxide layers existed in the deepest region and this layer consisted of a mixture of titanium oxide with aluminum oxide, whereas this layer was absent in Ca2+-implanted Ti–56Ni.