Advancing strength and counteracting embrittlement by displacive transformation in heterogeneous high-entropy alloys containing sigma phase

Lu, Wenjun1; Guo, Wenqi2; Wang, Zhangwei3; Li, Jianjun4; An, Fengchao1; Dehm, Gerhard5; Raabe, Dierk5; Liebscher, Christian H.5; Li, Zhiming6

2023-03-01

10.1016/j.actamat.2023.118717

ACTA MATERIALIA   Impact Factor & Quartile

1359-6454

1873-2453

Metallic alloy design for room temperature applications typically aims at avoiding undesired brittle intermetallic phases. In transition metal alloys, the sigma phase is particularly known as a harmful phase leading to serious embrittlement. Here, we develop a novel strategy that utilizes displacive transformation and heterogeneous structures to mitigate the embrittlement of sigma phase particles in high-entropy alloys (HEAs). A careful study of the deformation behavior reveals that the displacive transformation from face-centered cubic (FCC) to hex-agonal close packed (HCP) phase can effectively suppress the propagation of microcracks originated in these brittle sigma particles (310 +/- 52 nm) and contributes to high work hardening behavior during tensile deforma-tion. This is achieved by tuning the stacking fault energy of the FCC matrix by reducing the Ni content to promote transformation induce plasticity (TRIP) around the sigma phase in a non-equiatomic Fe34Mn20Co20Cr20Ni6 (at. %) HEA. Such TRIP effect can be optimized in various heterogeneous structures with bimodal grain sizes via simple cold-rolling (-60%) and subsequent annealing (30 min at 700 or 800 degrees C). The heterogeneously structured HEAs containing brittle sigma particles exhibit ultimate tensile strengths as high as-1.2 GPa while maintaining a ductility up to-50%. This is mainly attributed to the transformation induced stress-relaxation around the regions containing brittle sigma particles. The insights provide a new design strategy of combining TRIP effect and heterogeneous structures for developing strong and ductile alloys.

Sigma phase High -entropy alloys TRIP effect Heterogeneous structure Cracking

SCI

English

First ; Corresponding

open research fund of Songshan Lake Materials Laboratory[2021SLABFK05] ; Shenzhen Science and Technology Program[JCYJ20210324104404012] ; Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)[388544551] ; National Natural Science Foundation of China[51971248] ; Natural Science Foundation of Hunan Province["2021JJ10056","kq2202091"] ; National Science Foundation of China[2022JJ30712] ; Changsha Municipal Natural Science Foundation[11872380]

Materials Science ; Metallurgy & Metallurgical Engineering

Materials Science, Multidisciplinary ; Metallurgy & Metallurgical Engineering

WOS:000925679000001

PERGAMON-ELSEVIER SCIENCE LTD

MATERIALS SCIENCE

Web of Science

1.Southern Univ Sci & Technol, Dept Mech & Energy Engn, Shenzhen 518055, Peoples R China
2.Beihang Univ, Res Inst Aeroengine, Beijing 100191, Peoples R China
3.Cent South Univ, State Key Lab Powder Met, Changsha 410083, Peoples R China
4.Cent South Univ, Coll Mech & Elect Engn, Changsha 410083, Peoples R China
5.Max Planck Inst Eisenforschung, Max Planck Str 1, D-40237 Dusseldorf, Germany
6.Cent South Univ, Sch Mat Sci & Engn, Changsha 410083, Peoples R China

Lu, Wenjun,Guo, Wenqi,Wang, Zhangwei,et al. Advancing strength and counteracting embrittlement by displacive transformation in heterogeneous high-entropy alloys containing sigma phase[J]. ACTA MATERIALIA,2023,246.

Lu, Wenjun.,Guo, Wenqi.,Wang, Zhangwei.,Li, Jianjun.,An, Fengchao.,...&Li, Zhiming.(2023).Advancing strength and counteracting embrittlement by displacive transformation in heterogeneous high-entropy alloys containing sigma phase.ACTA MATERIALIA,246.

Lu, Wenjun,et al."Advancing strength and counteracting embrittlement by displacive transformation in heterogeneous high-entropy alloys containing sigma phase".ACTA MATERIALIA 246(2023).