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M: Metallphysik

M 30: Nanoskalige Materialien IV

M 30.3: Vortrag

Mittwoch, 26. März 2003, 17:00–17:15, IFW A

Grain size dependence of elastic properties and grain boundary structure in nanocrystalline nickel — •Shi-Jin Zhao, Karsten Albe, and Horst Hahn — TU Darmstadt, Fachbereich Materialwissenschaft, Petersenstr. 23, D-64287 Darmstadt

Molecular dynamics simulations were carried out to calculate the bulk modulus of nanocrystalline nickel for average grain sizes ranging from 1 to 20 nm in diameter at different temperatures. The simulations show that the bulk modulus is decreasing with decreasing grain size, which can be explained by a simple two phase model. Secondly, our results indicate that there exists a phase transition from nanocrystalline to an amorphous phase if r approaches 0.77 nm. In such a phase transition the bulk modulus remains constant. Detailed inspection of the local structures reveals that the grain boundary structure in nanocrystalline nickel is different from that of the amorphous bulk phase, which is in contrast to some earlier reports in the literature.