Keynote Speaker

Prof. Xizhang Chen

Wenzhou University

E-mail: chenxizhang@wzu.edu.cn

Title: Deposited Ductile-GPa CoCrNi-based FCC Medium Entropy Alloy with Continuously Precipitation by Directed Energy Deposition-Arc

Profile:

Chen Xizhang, Professor, Doctoral Supervisor, International Welding Engineer. He has long been committed to technological research and development in the fields of metal material design and manufacturing, welding, heat treatment and surface strengthening. He has won the honorary titles such as Leading Talent of Zhejiang Province's "Ten Thousand Talents Plan", Zhejiang Province Outstanding Engineer, Zhejiang Province "Qianjiang Scholar" Distinguished Professor, and the first-level talent of Zhejiang Province's "151 Talent Project". In recent five years, he has presided over and completed 1 international cooperation project of the Ministry of Science and Technology, 1 international cooperation project of the National Natural Science Foundation, 3 general projects, 10 projects such as Zhejiang Province's key research and development projects, and more than 20 enterprise entrusted projects. He has published more than 200 scientific and technological papers, including cover papers and highly cited papers in Journal of Materials Science & Technology (JMST), and obtained more than 20 authorized invention patents. He has presided over and won the Third Prize of Zhejiang Provincial Natural Science Award, the First Prize of Entrepreneurship Achievement of the China Invention Association, the Special Prize of Progress of the All-China Federation of Commerce, the First Prize of China Heat Treatment Industry Association, etc. As a core participant, he has won 3 first prizes, 2 second prizes and 1 third prize of provincial and ministerial scientific and technological progress awards. He serves as the Deputy Director of the Robotics and Automation Committee of the Chinese Welding Society, Executive Director of the Chinese Society for Heat Treatment, Member of the Additive Manufacturing Standards Committee of the Chinese Steel Standards Committee, Vice President of Zhejiang Welding Society, Vice President of Zhejiang Heat Treatment Society, President of Wenzhou Society for Metal Materials, President of Wenzhou Heat Treatment Society, etc. He also serves as Deputy Director of the Editorial Board, Associate Editor and Editorial Board Member of 6 international and domestic journals.

Abstract:

An L12-strengthened Co30Cr18Ni42Al5Ti5 medium-entropy alloy was fabricated via directed energy deposition (DED)-Arc technique, focusing on investigating the modulation mechanism of the process on L12 phase precipitation behavior. The results showed that the high heat input and moderate cooling rate features of DED-Arc process effectively suppressed the discontinuous precipitation (DP) behavior: the coarse columnar crystal structure significantly reduces the number of grain boundaries; moderate cooling rate promotes homogeneous distribution of Al/Ti elements and eliminates grain boundary segregation; This “coarse grain-element homogenization” synergy results in a high-density distribution of the L12 phase within the grain through a continuous precipitation (CP) behavior. Directly deposited alloys exhibit gigapascal strength (~1090 MPa) and high ductility (~30.9 %). Furthermore, subsequent heat treatment of the deposited alloys confirmed the thermal stability of the continuous L12 precipitation, with increased L12 phase fraction while maintaining “FCC+L12” structure. This work can provide guidance for the fabrication of L12-strengthened high-entropy alloys and medium-entropy alloys with excellent mechanical properties by additive manufacturing.

Keywords: Medium-entropy alloys, Additive manufacturing, L12 phase, Continuous precipitation, Mechanical properties