Thermal stability of nanostructured Cr-Ni alloys

Cr-2at% Ni and Cr-6at% Ni alloys were prepared by magnetron sputtering in argon gas. The grain size of the sputtered alloys were 83 and 69nm and in nano size. The addition of higher content of nickel reduces the grain size in the sputtered alloys. The both alloys are stable and maintain the nano-structure up to the annealing temperature of 673K at an annealing time of 7.2ks. Although the grain size of the alloys at a high temperature of 973K increases on increasing the annealing time, both the alloys maintain the nano size of the grain up to an annealing time of 10³s. The grain size of both the alloys at 973K definitely increases on further increasing the annealing time. Although the secondary nickel phase appears at the annealing process, the microhardness of the alloys decreases with the annealing time. The increase in grain size lowers the microhardness for the both alloys.