Effects of incorporation of Si or Hf on the microstructure and mechanical properties of Ti–Al–N films prepared by arc ion plating (AIP)

Ti–Al–N, Ti–Al–Si–N and Ti–Al–Hf–N films were deposited on 1Cr11Ni2W2MoV stainless steel by arc ion plating (AIP) with a Ti70Al30, a Ti60Al30Si10 and a Ti68Al30Hf2 cathode, respectively. The effects of Si or Hf addition on the composition, microstructure and mechanical properties of the Ti–Al–N films were investigated by EPMA, TEM, SEM, XRD, micro-hardness and wear tests. The results show that all the deposited films possessed B1 structure. With the incorporation of Si or Hf, the texture of Ti–Al–N films remarkably changed from preferred orientation of (220) to mixture broadened orientations of (111), (200) and (220), the mean crystallite size of Ti–Al–N decreased from ~ 90 nm to ~ 30 and ~ 15 nm and no peaks of crystalline Si3N4 were detected from XRD analyses. Due to the addition of Si or Hf, the micro-hardness of Ti–Al–N films increased remarkably from 23.5 Gpa to 33.6 or 29.5 GPa, and the wear resistance was also enhanced. The effects of incorporation of Si or Hf on the microstructure and mechanical properties of Ti–Al–N films are discussed.