Increased High Temperature Oxidation Resistance of Ni20Cr20Fe5Nb1Y_2O_3 Alloy with Nano-Sized Grains

摘要

The oxidation and tensile properties of a Ni20Cr20Fe5Nb alloy and a Ni20Cr20Fe 5Nbl Y_2O_3 alloy with nano-sized grains were compared with those of the comercial IN718 alloy. The oxidation resistance of the Ni20Cr20Fe5Nbl Y_2O_3 alloy was superior to that of the Ni20Cr20Fe5Nb and IN 718 alloys. This superior oxidation resistance was the result of both the formation of dense oxides on the surface of the alloy and the interruption of Cr migration in the alloy by the addition of Y2O_3. Moreover, the tensile property of the Ni20Cr20Fe5NblY_2O_3 alloy at room temperature and 400℃ was higher than that of the Ni20Cr20Fe5Nb and IN718 alloys by more than 300MPa (30%). This result can be attributed to the dispersion strengthening of Y_2O_3. The relatively low tensile strength at 600℃ and 800℃ of the alloys fabricated by mechanical alloying was attributed to grain refinement showing intergranular fracture at high temperatures.