Experimental Investigation of Phase Equilibria in the Co-Ta-Si Ternary System

Cuiping Wang; Xiang Huang; Liangfeng Huang; Mujin Yang; Peng Yang; Yunrui Cui; Jinbin Zhang; Shuiyuan Yang; Xingjun Liu

doi:10.3390/ma15093097

Experimental Investigation of Phase Equilibria in the Co-Ta-Si Ternary System

Materials (Basel). 2022 Apr 25;15(9):3097. doi: 10.3390/ma15093097.

Authors

Cuiping Wang^{1

2}, Xiang Huang^{1

2}, Liangfeng Huang^{1

2}, Mujin Yang³, Peng Yang^{1

2}, Yunrui Cui^{1

2}, Jinbin Zhang^{1

2}, Shuiyuan Yang^{1

2}, Xingjun Liu^{1

4}

Affiliations

¹ College of Materials and Fujian Provincial Key Laboratory of Materials Genome, Xiamen University, Xiamen 361005, China.
² Xiamen Key Laboratory of High Performance Metals and Materials, Xiamen University, Xiamen 361005, China.
³ Department of Mechanical and Energy Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
⁴ School of Materials Science and Engineering, Institute of Materials Genome & Big Data, Harbin Institute of Technology, Shenzhen 518055, China.

Abstract

In this work, two isothermal sections of the Co-Ta-Si ternary system at 900 °C and 1100 °C are constructed in the whole composition range via phase equilibrium determination with the help of electron probe microanalysis (EPMA) and X-ray diffraction (XRD) techniques. Firstly, several reported ternary phases G (Co₁₆Ta₆Si₇), G″ (Co₄TaSi₃), E (CoTaSi), L (Co₃Ta₂Si) and V (Co₄Ta₄Si₇) are all re-confirmed again. The G″ phase is found to be a kind of high-temperature compound, which is unstable at less than 1100 °C. Additionally, the L phase with a large composition range (Co_32-62Ta_26-36Si_10-30) crystallizes with a hexagonal crystal structure (space group: P6₃/mmc, C14), which is the same as that of the binary high-temperature λ₁-Co₂Ta phase. It can be reasonably speculated that the ternary L phase results from the stabilization toward low-temperature of the binary λ₁-Co₂Ta through adding Si. Secondly, the binary CoTa₂ and SiTa₂ phases are found to form a continuous solid solution phase (Co, Si)Ta₂ with a body-centered tetragonal structure. Thirdly, the elemental Si shows a large solid solubility for Co-Ta binary compounds while the Ta and Co are hardly dissolved in Co-Si and Ta-Si binary phases, respectively.

Keywords: Co-Ta-Si ternary system; Co-based superalloy; phase equilibria.

Abstract

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