Effect of carbon on microstructure and mechanical properties of Co-free medium-entropy alloys

Abstract

Effect of carbon content on the microstructure and mechanical properties of a Co-free C_x(CrFeNi)_100−x (x = 0, 0.5, 1, 1.5, 3, 4.5, and 6 at.-%) medium-entropy alloys were systematically investigated. The increase of carbon content promoted the phase structure of alloys changing from a single FCC phase to an FCC + M₂₃C₆ carbides dual-phase structure, accompanied by an apparent increase in yield strength and an uneven decrease in plasticity. The improvement of yield strength was attributed to the interstitial solid solution strengthening of carbon element and the precipitation strengthening of carbides. The decrease of plasticity was related to the formation of coarse carbides. The C_1.5(CrFeNi)_98.5 alloy exhibited an enhanced yielding strength of 265 MPa while maintained a considerable elongation of 38%.

KEYWORDS:

• Medium-entropy alloys
• carbon content
• microstructure
• mechanical properties

Disclosure statement

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

Additional information

Funding

This work was supported by National Natural Science Foundation of China: [Grant Number 52001181]; Youth Research Fund of Qinghai University: [Grant Number 2019-QGY-3].