Diffusion behavior and atomic mobilities for fcc CueCreNi alloys Gaochi Xu a , Yajun Liu a, * , Fuyue Lei a , Guang Sheng b , Zhitao Kang c, d a School of Materials and Energy, Guangdong University of Technology, Guangzhou, Guangdong 510006, PR China b Scientific Forming Technologies Corporation, Columbus, OH 43235, USA c School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA d Georgia Tech Research Institute, Georgia Institute of Technology, Atlanta, GA 30332, USA article info Article history: Received 1 April 2015 Received in revised form 13 June 2015 Accepted 27 June 2015 Available online 4 July 2015 Keywords: Diffusion Mobility fcc CueCreNi alloys CALPHAD abstract In this work, diffusion couples of fcc CueCreNi alloys annealed at 1373 K for 80 h are investigated. The interdiffusion coefficients are retrieved from common compositions of two diffusion couples, which are then combined with thermodynamic descriptions to explore atomic mobilities of Cu, Cr and Ni in fcc Cu eCreNi alloys within the CALPHAD framework. In order to confirm the quality of such kinetic charac- teristics, a comparison between calculated and experimentally measured concentration profiles of diffusion couples and diffusion paths in Gibbs triangle is made, where the agreement is excellent. The results of this study contribute to the establishment of a general Ni-based mobility database for alloy design. © 2015 Elsevier B.V. All rights reserved. 1. Introduction CueCreNi alloys feature good corrosion resistance and superior mechanical properties, which leads to their wide applications in shipbuilding industry [1]. In addition, such alloys can also be applied in electronic industry as corrosion-resistant conductor materials [2]. In order to further optimize the properties of CueCreNi alloys, which thus promote further applications in in- dustry, it is inevitable to explore the diffusion behaviors, as kinetic information plays a decisive role in alloy microstructure evolution [3]. Nowadays, CALPHAD-based kinetic technology has been well developed for materials scientists in alloy design. Within the framework of CALPHAD, atomic mobilities can be combined with thermodynamic parameters to gain further insights into diffusion characteristics, thereby facilitating investigation of composition and phase evolution in multi-component alloys. However, accurate atomic mobilities for multi-component alloys are still in shortage. The atomic mobilities for fcc CueNi and CreNi alloys have been reported by Wang et al. [4] and Engstrom and Agren [5], respec- tively. However, the temperature effect for interaction parameters of Cr and Ni was not included. The atomic mobilities for fcc CueCreNi alloys are still absent in the literature. Thus, the aim of this work is to investigate diffusion characteristics and related atomic mobilities for fcc CueCreNi alloys with the aid of CALPHAD technology. 1373 K is an important annealing temperature for casted Ni-based alloys. Thus, kinetic study at this temperature can help to gain more insights on how the inhomogeneity can be reduced. It is noted that the service temperature for Ni-based alloys is usually below 1000 K, at which grain boundary diffusion is sig- nificant. In view of such situation, diffusion characteristics for only 1373 K are explored in this work, and the atomic mobilities pre- sented can be used for alloy design around 1373 K. In the future, much work is still needed to assess the temperature dependence of the atomic mobilities for CreNi binary system, after which the temperature-dependence of atomic mobilities for CueCreNi ternary system can be well established. 2. Diffusion methodology 2.1. Establishment of diffusion modeling For Cu, Cr and Ni elements in fcc CueCreNi ternary alloys, the inter-diffusion fluxes defined in the number-fixed frame of refer- ence, can be expressed as [6]: J ! N Cu ¼ ~ D Ni CuCu VC Cu  ~ D Ni CuCr VC Cr (1) * Corresponding author. E-mail addresses: yajunliu@gatech.edu, pcbook@hotmail.com (Y. Liu). Contents lists available at ScienceDirect Journal of Alloys and Compounds journal homepage: http://www.elsevier.com/locate/jalcom http://dx.doi.org/10.1016/j.jallcom.2015.06.226 0925-8388/© 2015 Elsevier B.V. All rights reserved. Journal of Alloys and Compounds 649 (2015) 307e312