Microstructural examination of layered coatings by scanning electron microscopy, transmission electron microscopy, and atomic force microscopy

The structure of r.f. sputtered multilayer Ti-BN coatings was investigated by low-voltage scanning electron microscopy, energy-dispersive X-ray spectrometry, transmission electron microscopy, and atomic force microscopy. Appropriate specimen preparation methods are described for each technique; these included fracture of the substrate, masking the growing film to produce a taper section, and ion-beam milling of embedded cross sections. Correlation of scanning electron micrographs with atomic force images was facilitated by the presence of similar composition contrast in both cases. Quantitative X-ray microanalysis of the layers was performed using the φ(ϱz) approach. The crystal structures of nanocrystalline grains nucleated as a result of interdiffusion reactions during thermal annealing were identified by selected-area electron diffraction and convergent-beam microdiffraction as α-titanium and f.c.c. titanium nitride.