Browsing by Author "Akbas, N"

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    Investigation on the tribology of Zr ion implanted tool steel
    Akbas, N; Oztarhan, A; Monteiro, OR; Brown, IG
    AISI D3 tool steel was ion implanted with zirconium and the improvement in surface tribological properties investigated. The Zr ion implantation was done using a metal vapor vacuum ire (Mevva) broad-beam ion source, with a mean ion energy of 130 keV and at doses of 3.6 x 10(16), 5 x 10(16) and 1 x 10(17) ions/cm(2). Wear, friction and hardness of the implanted samples were measured and compared to the performance of unimplanted steel. The wear resistance was increased by about a factor of two, the friction remained about the same or was possibly increased by a small amount and the near-surface hardness was improved by a factor of live or more by the ion implantation. We also investigated the effect on the Zr implantation profile of the multi-component energy distribution of the ion beam. (C) 2002 Elsevier Science B.V. All rights reserved.
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    High fluence effects on ion implantation stopping and range
    Selvi, S; Tek, Z; Öztarhan, A; Akbas, N; Brown, IG
    We have developed a code STOPPO which can be used to modify the more-widely used ion implantation codes to more accurately predict the mean nuclear and electronic stopping power, preferential sputtering and range of heavy ions in monatomic target materials. In our simulations an effective atomic number and effective atomic mass are introduced into conveniently available analytical stopping cross-sections and a better fitting function for preferential sputtering yield is carefully evaluated for each ion implantation. The accuracy of the code confirmed experimentally by comparison with measured Rutherford backscattering spectrometry (RBS) concentration profiles for 130 keV Zr ions implanted into Be to fluences of 1 x 10(17), 2 x 10(17) and 4 x 10(17) ions/cm(2). We find a steady increase in the mean nuclear and electronic stopping powers of the target; the increase in nuclear stopping power is much greater than the increase in electronic stopping power. (C) 2004 Elsevier B.V. All rights reserved.