Invited speaker

Prof. Shingguo Ma

Taiyuan University of Technology

TEL:13503544997

Title: Mechanical behavior and deformation mechanism of Ni50Cr20Fe20Al5Ti5 medium-entropy alloys

Profile:

Shengguo Ma, Associate Professor and Doctoral Supervisor at the College of Aeronautics and Astronautics, Taiyuan University of Technology, has received the title of young excellent talents supported by the Three Jin Talents Program in Shanxi Province, and acted as the young editorial board member in Journal of Materials Engineering and Journal of Aeronautical Materials. He has won the first prize in natural science in Shanxi Province (the third author). He has also been selected for two consecutive years in the Top 2% Global Scientists List released by Stanford University. He has received the support of National Natural Science Foundation of China, the Natural Science Foundation of Shanxi Province, and the open project Program of the State Key Laboratorys. At least 50 research papers has been published in the Journals of Acta Materialia, Scripta Materialia, Materials Science and Engineering A, Materials and Design, etc. Five national invention patents were authorized, and one monograph was authored.

Abstract:

A Co-free non-equiatomic Ni_2.5CrFeAl_0.25Ti_0.25 medium-entropy alloy (MEA) with an excellent strength-ductility synergy was fabricated, which shows a three-level phase structure composed of face-centered cubic (FCC), L1₂ (ordered FCC), and Cr-rich body-centered cubic (BCC) phase by thermomechanical processing. Specifically, the aged sample displays the outstanding yield tensile strength (YTS, ~1.2 GPa), ultimate tensile strength (UTS, ~1.6 GPa) and work-hardening rate (WHR, ~4.5 GPa) values as well as an acceptable tensile plasticity of ~16.6%. Theoretical calculations suggest that precipitation strengthening significantly contributes to achieving the fascinating tensile strength among various strengthening contributors. Further analyses reveal that multiple nanoscale stacking-fault (SF) networks are activated during plastic deformation in the aged alloy. Accordingly, the dual effects consisting of the three-level phase structure and SF networks lead to the combination of excellent tensile strength and strain-hardening capacity. Furthermore, the Ni_2.5CrFeAl_0.25Ti_0.25 MEA also shows an excellent strength-ductility combination at cryogenic temperature, in which the low-temperature tensile yield strength and ultimate tensile strength were respectively about 1.4 GPa and 2 GPa, followed by about 21% tensile plasticity.