Abstract
In this report we briefly review the current state-of-the-art and challenges in determining point defect properties from first-principles calculations as well as from experimental measurements in titanium nickelid. . Based on the vacancy formation energy and their activation energy for vacancy migration in TiNi, vacancy mediated diffusion mechanism was examined. The behavior of vacancy defects in the TiNi structural phase transition has been described.
Highlights
Fe61Al39 and Fe63Al37 in B2 structure were studied by positron annihilation lifetime spectroscopy
In the reference well-annealed state average positron lifetime corresponds to a delocalized positron state, i.e. the vacancy concentration in a sample lower than the positron annihilation spectroscopy (PAS) method threshold limit
MATEC Web of Conferences sample within temperature range 600К
Summary
Investigating diffusion processes in titanium nickelid alloys sharpened several issues on types and characteristic features of point defects. Investigating Ni diffusion in relation to pressure [2] showed that activation volume of diffusion Ni in TiNi within experimental error is equals zero. This could imply that diffusion mechanism is interstitial mediated or that there are structural vacancies in the intermetallic compound. As discussion of the diffusion mechanism in B2 intermetallic, causes disputes [3,4,5], research of point defects in TiNi is relevant. Some authors [6,7,8,9] state that point defects configuration of a B2 phase can play an important role in nucleation and growth processes of martensitic phase
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