Effects of Al Content on Microstructure and Mechanical Property of CrAlN Coating Synthesized by Reactive Magnetron Sputtering

A series of CrAlN coatings with different Al content were synthesized on high-speed steel(M2)substrate by reactive direct current(DC)magnetron sputtering.The influences of Al content on the microstructure and mechanical property of CrAlN coatings were studied by scanning electron microscopy(SEM),X-ray diffraction(XRD),energy dispersive spectrum(EDS)and nano-indentation techniques,respectively.The results indicate that the coatings exhibit only fcc c-CrN phase when Al content is less than 65 at%,and fcc c-CrN and c-AlN phases when Al content is 78 at%.The coating with Al content of 60 at%exhibits high hardness and elastic modulus.The maximum hardness and elastic modulus values could reach 36.8 GPa and 459.5 GPa,respectively.