Effect of Aging Treatment on Microstructure and Properties of the Fe₅₅(CoCrNi)₁₀(MoV)₅C₅ Medium-Entropy Alloy

Abstract

In this study; the effect of aging treatment for 4 h at 600–1000 °C on the microstructure and properties of a Fe55(CoCrNi)10(MoV)5C5 medium-entropy alloy (MEA) was investigated. After the alloy was aged at 800 °C, a large number of granular and rod-shaped particles are formed throughout the face-centered cubic (FCC) matrix. The average particle diameter was measured to be approximately 46 nm, and the result of transmission electron microscopy (TEM) analysis verified that these secondary precipitates are VC carbides, which plays an important role for pinning dislocations and hindering dislocation movement. Therefore, the hardness and ultimate tensile strength of the alloy at this state increased from 253 HV, 322 MPa in cast condition to 326 HV, 626 MPa, respectively, while remaining relatively good elongation (6.2%). As the aging temperature increases, the volume fraction of the VC carbides decreased while its sizes increased; thus, the dispersion strengthening effect was reduced, resulting in the decrease in the hardness and strength.

Keywords

• medium-entropy alloy
• aging treatment
• precipitation
• microstructure
• mechanical property