Site preference of Hf dopant in Ni sub(3)Al alloys: A perturbed angular correlation study

• Published in: Journal of alloys and compounds 2015-02, Vol.622, p.541-547
• Main Authors: Ivanovski, V N, Cekic, B, Umicevic, A, Barudzija, T, Schumacher, G, Madarevic, I, Koteski, V
• Format: Article
• Language: English
• Subjects: Alloys; Aluminum; Aluminum base alloys; Angular correlation; Hafnium; Intermetallic compounds; Intermetallics; Nickel aluminides; Transformations
• ISSN: 0925-8388
• DOI: 10.1016/j.jallcom.2014.10.132

Perturbed angular correlation measurements of the hyperfine interactions of the super(181)Ta probe in the polycrystalline intermetallic Ni sub(3)Al doped with 0.5 and 5 at.% Hf were performed in the temperature range 78-1230 K. The observed local hyperfine fields at the super(181)Hf/ super(181)Ta probe showed that Hf atoms are substituting on Al sites in the Ll sub(2) structure of Ni sub(3)Al. The two minor electric quadrupole interactions that were found for each Ni sub(3)Al alloy are discussed taking into account the Ll sub(2) cubic structure and its two tetragonal distortions: D0 sub(22) and L6 sub(0). The presence of two tetragonal transformations of the parent cubic Ll sub(2) lattice in 0.5 at.% Hf and 5 at.% Hf doped Ni sub(3)Al was revealed by X-ray diffraction. The ab initio calculations, performed with the projector augmented wave method correctly reproduce the experimental results and enable discussion on the structural and electronic properties of the polycrystalline alloys. The experimental and theoretical investigations showed that hafnium additions prefer aluminum sites in Ni sub(3)Al.