Structures and microhardness of nanostructured Cr–Ni-sputtered alloy

Nanostructured Cr–xNi alloys were prepared by magnetron sputtering in low pressure argon gas, where x varied from 0 to 20 at%. The structure and microhardness of the alloys were observed by TEM (microscopy) and Vickers hardness testing, respectively. The crystal structure of the sputtered alloys was BCC. The addition of nickel to chromium decreases the grain size of the Cr–Ni alloys and the grain sizes of the alloys changed from 88 nm for Cr to 30 nm for Cr-20 at% Ni alloys. The microhardness of the Cr–Ni alloys showed the maximum around 5 at% Ni. The increase in nickel content above 5 at% lowers the microhardness of the alloys, although the grain size of the Cr–Ni decreases. The abnormal tendency against grain size change was discussed in terms of the characteristics of the grain boundaries in the alloys.