THE MICROSTRUCTURES AND SUPERHARDNESS EFFECT OF THE POLYCRYSTALLICE FaN/TiN AND TaWN/TiN SUPERLATTICE FILMS

The polycrystalline TaN/TiN and TaWN/TiN superlattice films have been grown byreactive magnetron sputtering. The microstructures and microhardness of the superlattice films havebeen studied with X-ray diffraction (XRD), transmission electron microscopy (TEM) and microhardnesstester. The results show that the crystal structure of the component materials in TaN/TiN and TaWN/TiNsuperlattice films are faced-center cubic (FCC) and have a epitaxially grown mode of polycrystallinity. Thecoherent strain has been produced due to the coherent interfaces. TaN/TiN and TaWN/TiN superlatticefilms all have superhardness effect and have hardness maximum values HK=40.0 and 50.0 GPa with amodulation period at 9.0 and 5.6 nm respectively. The authors have proposed that the lattice mismatchaffect the microhardness value and the peak position where hardness gets its maximum. The main reasoncausing hardness anomalies is the inhibition of dislocation motion by alternating stress fields of interfacial coherent strain.