中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 36 No. 1 January 2026 |
（a Fujian Key Laboratory of Surface and Interface Engineering for High Performance Materials, School of Materials Science, Xiamen University, Xiamen 361005, China;
b Xiamen Key Laboratory of High Performance Metals and Materials, School of Materials Science, Xiamen University, Xiamen 361005, China;
c School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China）
Abstract:Low-density superalloys often exhibit low yield strength in the intermediate temperature range (300-650 °C). To enhance yield performance in this range, the CALPHAD method was used to design a new Co-based superalloy. The Co-30Ni-10Al-3V-6Ti-2Ta alloy, designed based on γ？ phase dissolution temperature and phase fraction, was synthesized via arc melting and heat treatment. Phase transition temperatures, microstructure evolution, and high-temperature mechanical properties were characterized by differential scanning calorimetry, scanning electron microscopy, dual-beam TEM, and compression tests. Results show that the alloy has low density (8.15 g/cm3) and high γ？ dissolution temperature (1234 °C), along with unique yield strength retention from room temperature to 650 °C. The yield strength anomaly (YSA) is attributed to high stacking fault energy and activation of the Kear-Wilsdorf locking mechanism, contributing to superior high-temperature stability of the alloy. The yield strength of this alloy outperforms other low-density Co-based superalloys in the temperature range of 23-650 °C.
Key words: Co-based superalloy; calculated phase diagram; mechanical property; sub microstructure evolution; γ？ phase
