Effects of Zr and Nb on d electrons in NiAl alloy studied by coincidence positron annihilation spectroscopy

The behavior of d electrons in pure Ni, Zr, Nb metals and NiAl-based alloys (NiAl, Ni50Al48Zr2 and Ni50Al48Nb2) has been studied by two-detector coincidence system of Doppler broadening of positron annihilation radiation. It has been found that the probability of positron annihilation with 3d electrons in binary NiAl alloy is relatively low due to the Ni 3d–Al 3p interactions. The additions of Zr or Nb atoms to NiAl alloy lead to the enhancement of d–d interactions and thus the d electron signal in the spectrum. The d electron signal in the spectrum of Ni50Al48Nb2 alloy is higher than that of Ni50Al48Zr2 alloy, that is, the Nb addition is more effective in enhancing the d–d interactions in NiAl alloy compared with the Zr addition.