Modeling the amorphous structure of mechanically alloyed amorphous Ni30Nb70 using anomalous wide-angle X-ray scattering and reverse Monte Carlo simulations

The atomic short range order of a mechanically alloyed amorphous Ni30Nb70 alloy (a-Ni30Nb70) was determined using two total structure factors S(K) derived using anomalous wide angle X-ray scattering (AWAXS) measurements as input data for reverse Monte Carlo (RMC) simulations. The coordination numbers (Nij) and interatomic distances (Rij) for the first neighbors were obtained. The chemical short range order (CSRO) and the chemical medium range order (CMRO) of a-Ni30Nb70 were investigated using the Cowley-Warren parameter αCW. The results suggest a preference for homopolar pairs or clusters in the first and second coordination shells. The angular distribution of bonds between first neighbor atoms is taken as evidence for the presence of distorted polyhedral units with triangular and square faces in the atomic structure of a-Ni30Nb70.