The 3d-shell electrons in NiAl-based alloys containing Cr and Co studied by positron annihilation

We report that the 3d electron signal for the transition metals (Cr, Co, and Ni) and the NiAl-based alloys (NiAl, Ni48Al45Cr7, and Ni48Al45Co7) can be extracted by a two-detector coincidence system from the Doppler broadening of positron annihilation radiation. The experimental results show that the 3d electron signal for the undoped NiAl alloy is relatively low. The additions of Cr and Co to NiAl alloy lead to an increase in the probability of positron annihilation with 3d electrons. The 3d electron signal in the spectrum of Ni48Al45Co7 alloy is higher than that of Ni48Al45Cr7 alloy. The Co addition is more effective in enhancing the d-d interactions in NiAl alloy as compared with the Cr addition.