Study on mechanical properties of CoCrFeNiN_x high entropy alloy films based on nanoindentation

ABSTRACT

CoCrFeNiN_x films were prepared by magnetron sputtering under different nitrogen flow ratios (R_N). The mechanical properties were measured by nanoindentation. The results show that with the increase of R_N, the content of N in the films increases, and the contents of Cr, Co, Fe and Ni decrease with basically unchanged composition ratio. The films have very dense structure with uniformly distributed elements. With increasing R_N the film changes from metal solid solution phase with weak FCC (111) preference to nitrogenous solid solution phase with FCC (200) strong preference, then to FCC (200) weak preference, finally to near amorphous. The hardness and elastic modulus increase with R_N, but are almost independent of the strain rate. The CoCrFeNiN_x films with R_N = 20% and R_N = 60% have lower creep deformations and demonstrate better creep properties, probably related to their composition, structure (oriented growth, crystallinity, defects, etc.) and residual stress.

KEYWORDS:

• CoCrFeNiN_x films
• nitrogen flow ratio
• hardness
• elastic modulus
• creep properties

Disclosure statement

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

Additional information

Funding

This project is supported by the National Natural Science Foundation of China (Grant No. 51301087), the Opening Project of Jiangsu Key Laboratory of Advanced Structural Materials and Application Technology (Grant No. ASMA201708), the Innovative Foundation Project of Nanjing Institute of Technology (Grant No. CKJB The Innovative Foundation Project of Nanjing Institute of Technology 201701).