fulltext - Appl. Phys. A 90, 347349 (2008) DOI:...

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DOI: 10.1007/s00339-007-4280-6 Appl. Phys. A 90, 347–349 (2008) Materials Science & Processing Applied Physics A f.l. bregolin 1 m. behar 1, ± f. dyment 2 Diffusion study of 15 N implanted into α -Ti using the nuclear resonance technique 1 Instituto de Fisica, UFRGS, Caixa Postal 15051, 91501-970 Porto Alegre, RS, Brasil 2 Consejo Nacional de Investigaciones Cientificas y T´ecnicas (CONICET), Buenos Aires, Argentina Received: 22 May 2007 / Accepted: 15 August 2007 Published online: 25 September 2007 • © Springer-Verlag 2007 ABSTRACT The diffusion of 15 Nin α -Ti was studied in the 673–1023 K temperature range by using the ion implantation and nuclear resonance techniques. The measurements show that the diffusion coefficients follow an Arrhenius behavior D ( T ) = D Q / RT 0 ,whe re D 0 = ( 1 . 1 ± 0 . 8 ) × 10 7 m 2 s 1 and Q = ( 183 ± 2 ) kJ / mol. A comparison with previous results is also given. PACS 66.30.Jt; 85.40.Ry 1 Introduction A clear relationship exists between Hf, Zr and Ti. They belong to group IV of the periodic table, are highly reac- tive and transform from the bcc ( β -phase) to the hcp ( α -phase) at low temperatures. Although the self and substitutional diffusion behavior in the β -phase was extensively studied [1], this is not the case for the α -phase. The main reason is the small expected diffusion coefficients ( D < 10 17 cm 2 s 1 ), which strongly reduces the use of conventional analyzing techniques. However, much work was done in the last 20 years when the Rutherford backscattering (RBS) and resonant nuclear re- action (NRA) techniques were applied in the diffusion study of solutes in α -Ti. Consequently, the results of an extensive and systematic study have shown that the substitutional and interstitial impurities follow a regular diffusion mechanism characterized by an Arrhenius behavior [2, 3]. This behavior was at variance with what was observed for α -Zr. In this last case, for most of the solutes, an anomalous diffusion behavior was observed. It revealed that different mechanisms operate for each matrix, as discussed in [3]. For α -Ti, the role played by the impurity level of the ma- trix is not clear. In most of the cases the diffusion behavior was not affected by the impurity level of the α -Ti – see for example the diffusion of Pb [3] and Sn [4], among others. However, for the substitutional atoms Ta [5] and Al [6, 7], the interstitial ± Fax: +55-51-3308-6510, E-mail: behar@if.ufrgs.br atom O [8] and for self-diffusion [7, 9] it was observed that the impurity level of α -Ti had a strong influence on the respective diffusivity. The diffusion behavior of N in α -Ti is very important due to the strong influence of nitrogen on its mechanical prop- erties. The N diffusion into α -Ti was first and only studied by Anttila et al. [10]. They performed the experiment using the NRA technique with a 99 . 9% purity sample. We have un- dertaken the present work with a sample of higher purity in order to check if the impurity content affects the diffusion of α -Ti. We used the ion-implantation technique to intro- duce the 15 N into the α -Ti sample and the resonant nuclear reaction 15 N ( p ,αγ) 12
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This note was uploaded on 10/08/2009 for the course CME MAT E 630 taught by Professor Dr. during the Fall '09 term at University of Alberta.

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fulltext - Appl. Phys. A 90, 347349 (2008) DOI:...

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