Effects of Trace Ce Addition on Hot Deformation Behavior of Cu-0.8 Mg Alloy Guoqiang Sun, Yong Liu, Baohong Tian, Yi Zhang, Zhengbin Gu, and Alex A. Volinsky (Submitted December 13, 2018; in revised form January 13, 2020; published online February 10, 2020) Hot deformation tests of Cu-0.8 Mg and Cu-0.8 Mg-0.15 Ce alloys were carried out with a Gleeble-1500D thermal simulator in the temperature range of 500-850°C and the strain rate range of 0.001-10 s 21 . Based on compression tests, flow stress–strain curves and processing maps of Cu-0.8 Mg and Cu-0.8 Mg-0.15 Ce alloys were plotted, and constitutive equations of the two alloys were constructed. The microstructure of the two alloys under different hot deformation conditions was observed and analyzed by optical microscopy. The trace addition of Ce restricted the movement of dislocations, promoted dynamic recrystallization, increased the flow stress and activation energy for hot deformation and enlarged the hot working region compared to the alloy without trace Ce addition. Keywords constitutive model, Cu-0.8 Mg alloy, Cu-0.8 Mg-0.15 Ce alloy, hot deformation tests, processing maps 1. Introduction Copper alloys are widely used in different industries, including electrical, electronics, machinery manufacturing, chemical, construction, national defense and many other industries due to their good conductivity, corrosion resistance, plasticity, formability and durability (Ref 1–4). With the rapid development of science and technology, copper alloys are used in many applications and the demands for these alloys are still growing. Due to low mining cost, good physical properties and abundant natural deposits, copper is considered as a new functional material with good applications potential and development prospects. At the same time, more stringent performance requirements are put forward for copper and its alloys. Researchers have also developed many new copper alloys, such as medium-strength and high-conductivity Cu-Fe-P alloy (Ref 5, 6), high-strength and medium-conductivity Cu-Ni- Si alloy (Ref 7, 8), high-strength and high-conductivity Cu-Cr- Zr alloy (Ref 9, 10) and so on. To improve the comprehensive properties of copper and its alloys, trace elements are often added at optimal concentration. For example, Si can assist in deoxidation purification and improve the fluidity of the alloys (Ref 11). Sn can inhibit the aging process of Mg (Ref 12). Dislocation pinning is improved by the precipitation of added Ce, and both mechanical and chemical properties of the alloy can be improved remarkably by adding P and Ce (Ref 13, 14). Cu-Mg is a multi-component copper alloy with high hardness and electrical conductivity, which is used in railway contact wires, tramlines, aircraft antennas and so on. Lots of scholars have performed research on Cu-Mg alloys, but special pro- cessing methods are needed to manufacture copper alloy with high strength and high conductivity. However, these methods are not yet suitable for commercial use. With the increasing speed of high-speed railways, the properties of contact wire materials also need to be improved. There are stricter require- ments for materials, but less research has been done on the hot deformation of copper alloys with high Mg content. Zhang et al. (Ref 15) studied the hot deformation behavior of the Cu- Zr-Cr-Ce alloy and found that trace addition of Ce increases flow stress and promotes dynamic recrystallization of the alloy. Therefore, the addition of Ce may further improve the hot workability of the Cu-Mg alloy. In this paper, hot deformation experiments with Cu-0.8 Mg and Cu-0.8 Mg-0.15 Ce alloys under different deformation conditions were carried out using a Gleeble-1500D thermal deformation simulator. Based on the data obtained from the two tested alloys, the flow stress–strain curves and the processing maps are plotted, and the constitutive equations are constructed. The microstructure of the two alloys under different hot deformation conditions is observed and analyzed by optical microscopy. These results provide reference for industrial production processes. Guoqiang Sun, School of Material Science and Engineering, Henan University of Science and Technology, Luoyang 471023, China; Yong Liu, School of Material Science and Engineering, Henan University of Science and Technology, Luoyang 471023, China; Collaborative Innovation Center of Nonferrous Metals, Luoyang 471023 Henan Province, China; and Henan Key Laboratory of Advanced Non-Ferrous Materials, Luoyang 471023, China; Baohong Tian, School of Material Science and Engineering, Henan University of Science and Technology, Luoyang 471023, China; and Collaborative Innovation Center of Nonferrous Metals, Luoyang 471023 Henan Province, China; Yi Zhang, School of Material Science and Engineering, Henan University of Science and Technology, Luoyang 471023, China; and Henan Key Laboratory of Advanced Non-Ferrous Materials, Luoyang 471023, China; Zhengbin Gu, National Laboratory of Solid State Microstructures, Department of Materials Science and Engineering, College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, China; and Alex A. Volinsky, Department of Mechanical Engineering, University of South Florida, Tampa 33620. Contact e-mails: liuyong@haust.edu.cn and volinsky@usf.edu. JMEPEG (2020) 29:776–786 ÓASM International https://doi.org/10.1007/s11665-020-04619-x 1059-9495/$19.00 776—Volume 29(2) February 2020 Journal of Materials Engineering and Performance