Diamond nucleation on Ni3Al substrate using bias enhanced nucleation method

Diamond deposition with positive and negative bias enhanced nucleation (BEN) pretreatments on mirror-polished polycrystalline Ni3Al substrates has been investigated, respectively. It was found that diamond deposition on the substrates under both biasing exhibited significant variations among grains of different orientations. The substrate surface was found to be rough in the case of negative biasing, whereas it was smooth in the case of positive biasing. Thus, the correlation of the crystallographic orientation of grains on the samples with the diamond nucleation behavior was systematically characterized for the case of positive biasing by electron backscattered diffraction method with scanning electron microscopy. Diamond deposition on Ni3Al grains near (111) orientation results in higher nucleation densities, while the densities are low on (110) and (100) oriented grains. Also, the interfacial microstructure between diamond deposited and Ni3Al was characterized by cross-sectional transmission electron microscopy.