Investigating the influence of phonons on the point defect properties of D011 NiAl3 by means of an embedded-atom potential, the present work demonstrates the importance of this factor, responsible for a large enhancement of the amounts of Al intrinsic and Ni interstitial defects, hence a complete change in the expected point defect structure of the compound, with possible consequences on matter diffusion. Moreover, new eigenfrequencies, above the DOS of the perfect crystal, were obtained around isolated Al interstitials and antisites, confirming the role of extra Al-Al bonds in the rise of upper frequencies, a feature already noted in Ni3Al. However, such frequencies were also surprisingly detected in Ni-rich alloys containing interstitial Ni, which suggests a Ni-induced stiff coupling of Al atoms.

Point Defect Phonons in Intermetallics - NiAl3 by Atomic-Scale Simulation. D.Tingaud, R.Besson: Physica Status Solidi C, 2009, 6[9], 2008–11