Microstructural evolution in CoCrFeNi and CoCrCuFeNi alloys processed by autogenous fusion welding

Abstract

In this work, CoCrFeNi and CoCrCuFeNi multi-principal element alloys were welded using an autogenous gas tungsten arc welding process. Tensile testing, microhardness, X-ray diffraction, scanning electron microscopy, electron back scattered diffraction techniques were used to study the mechanical properties, crystal structure and microstructures of the base metals (BMs) and welds. It was found that CoCrFeNi alloy was easily weldable while CoCrCuFeNi alloy produced transverse cracks. Only 13.5% decrease in ultimate tensile strength as compared to its BM was observed in CoCrFeNi alloy. Whereas poor tensile properties were observed in CoCrCuFeNi alloy due to Cu segregation and micro-cracks. Fractography analysis of the BM and weld specimen shows ductile failure in both the alloys.

KEYWORDS:

• High entropy alloy
• multi-principal element alloy
• welding
• GTAW
• fractography
• microstructural evolution

Acknowledgements

We are very thankful to Dr. C. P. Ramanarayanan, Vice-Chancellor, DIAT (DU) for constant support. This work was supported by Science & Engineering Research Board, Department of Science & Technology (DST), India (No: EEQ/2017/000724). We are grateful to the Director, DMRL, Hyderabad for supporting miniature tensile tests.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by Department of Science and Technology, Ministry of Science and Technology, India [grant number EEQ/2017/000724].