Study On Diffusion Mobilities For FCC Phase Of The Ni-Cu-Mn And Ni-Cu-Cr Ternary Systems

Due to the excellent heat resistance, good oxidation resistance and good corrosion resistance, nickel-base alloys are often utilized in extreme environment. Ni-Cu alloys are very important corrosion resistance alloys and find wide applications in industry such as petrochemical engineering, electricity and electronic industry. Thermodynamics and diffusion kinetics play key roles in the process of materials design and manufacturing. So far, the thermodynamic databases for Ni-base alloys are mature, but the diffusion mobility databases are limited even for ternary systems. Two systems, Ni-Cu-Mn and Ni-Cu-Cr, were chosen as the research target in the present work. The diffusion coefficients were comprehensively reviewed and the diffusion mobility parameters were obtained by using the CALPHAD method. The ternary databases established in the present work are parts of a comprehensive diffusion mobility database for nickel-base alloys. The main results are listed as follows.(1) The accurate thermodynamic parameters of the Ni-Cu-Mn ternary system were chosen from the literature. All the diffusion coefficients of FCC Ni-Cu, Ni-Mn, Cu-Mn and Ni-Cu-Mn systems were reviewed, and the hypotheses for inpurity mobility parameters QCu Mn and QNiMn were made. The interdiffussion coefficients of the Ni-Cu binary at 1073 K, 1123 K, 1273 K and Ni-Mn binary at 1223 K, 1273 K were measured in the present work. Based on the available experimental data and thermodynamic parameters, the diffusion mobilities for the Ni-Cu-Mn system were critically assessed using the DICTRA(DIffusion Controlled TRAnsformation) software package. The assessed diffusion mobility parameters were validated by the caculated of diffusion coefficients and interdiffusion behaviors in diffusion couple experiments, such as concentration profiles and diffusion paths.(2) The accurate thermodynamic parameters of the Ni-Cu-Cr ternary system were chosen from the literature. Based on the previous work, the hypotheses of inpurity mobility parameters QCu Cr and QCrCu in Cu-Cr binary were made. The interdiffussion coefficients of the Ni-Cu-Cr ternary at 1173 K, 1273 K and 1373 K were measured in the present work. Based on the available experimental data and thermodynamic parameters for the Ni-Cu-Cr alloys, the diffusion mobility parameters of Ni, Cu and Cr for Ni-Cu-Cr system were assessed by using the DICTRA software package. The prediction of diffusion coefficients and interdiffusion behaviors was conducted, which agrees well with the experimentally measured data. A comprehensive comparison validates the reliability of the assessed diffusion mobility.