Fatigue behavior of CoCrFeMnNi high-entropy alloy under fully reversed cyclic deformation

Tian, Yanzhong; Sun, Shijie; Lin, Hao-Hsiung; Zhang, Z.F.

doi:10.1016/j.jmst.2018.09.068

Cited by 131 publications

(28 citation statements)

References 42 publications

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“…Different results were obtained by other authors when ultra-fine-grained HEA was explored. They reported a strong dislocation activity with no twinning under cyclic loading [24]. This can also be the supporting findings of this work where only larger grains were subjected to the extensive (nano) twinning and dislocation slip as is documented in Figure 6e,f.…”

Section: Discussionsupporting

confidence: 85%

“…This can also be the supporting findings of this work where only larger grains were subjected to the extensive (nano) twinning and dislocation slip as is documented in Figure 6e,f. The crack initiation mechanism is therefore different when compared with coarse grain microstructure or refined one having narrow grain size distribution without abnormally large grains as reported by some authors [24,26]. The localization of plastic deformation to the conveniently situated in the abnormally large grain results in the formation of micro-cracks within the grain followed by final brittle fracture without any typical sign of fatigue crack propagation.…”

Section: Discussionmentioning

confidence: 89%

“…The resulting microstructure is ultra-fine-grained, submicron on average, when compared with the CoCrFeNiMn HEAs prepared by other methods where the grain size is usually few orders of magnitude larger [11,26,28]. It was demonstrated that Cantors alloy can be refined by post heat treatment to obtain similar microstructure as investigated [24]. However, the processing history can influence the resulting behaviour of the material [18].…”

Section: Discussionmentioning

confidence: 89%

“…Also, the predominant deformation mechanism is changed from dislocation glide to the diffusional creep when dispersion is present in the HEA microstructure [21,22]. The HEA response to the dynamic loading was investigated only in a few works [15,[24][25][26]. High cycle fatigue data obtained on a coarse-grained HEA (average grain size of 245 µm) suggested that the fatigue endurance limit is just below the alloy tensile yield strength.…”

Section: Introductionmentioning

confidence: 99%

“…Cr-Mn base oxide inclusions of the size up to 5 µm present in the microstructure were determined as the fatigue crack initiation sites and deformation twins formed during cycling and their boundaries act as the fatigue crack propagation paths in this coarse-grained alloy [15]. The effect of the grain size on the fatigue behaviour of an ultra-fine-grained CoCrFeMnNi HEA with fully recrystallized microstructure, processed by cold rolling of cast ingots and annealing was investigated by other authors in [24]. Their findings indicate that the grain refinement has a positive effect on both the applicable stress amplitude and the fatigue endurance limit even though in the ultra-fine-grained structure the cracks were present due to the material processing.…”

Section: Introductionmentioning

confidence: 99%

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Fatigue Behaviour and Crack Initiation in CoCrFeNiMn High-Entropy Alloy Processed by Powder Metallurgy

Chlup

Fintová

Hadraba

et al. 2019

Metals

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Single-phase equiatomic five-element high entropy alloy CoCrFeMnNi was prepared by powder metallurgy. Two materials with ultra-fine-grained microstructure were prepared by spark plasma sintering (SPS) of ball-milled powder at two sintering times (5 and 10 min), assigned as HEA 5 and HEA 10, respectively. Basic microstructural and mechanical properties were evaluated. The median grain size of the microstructures was determined to be 0.4 and 0.6 µm for HEA 5 and HEA 10, respectively. The differences in the microstructure led to a significant change in strength and deformation characteristics evaluated at room temperature. The effect of cyclic loading was monitored by three-point bending fatigue test. The results show that even relatively small change in the microstructure causes a significant effect on fatigue life. The fatigue endurance limit was measured to be 1100 MPa and 1000 MPa for HEA 5 and HEA 10, respectively. The detailed fractographic analysis revealed that abnormally large grains, localised in the microstructure on the tensile loaded surface, were a typical fatigue initiation site. The formation of (nano) twins together with dislocation slips caused the crack nucleation because of the cyclic loading.

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Section: Discussionsupporting

confidence: 85%

Section: Discussionmentioning

confidence: 89%

Section: Discussionmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Fatigue Behaviour and Crack Initiation in CoCrFeNiMn High-Entropy Alloy Processed by Powder Metallurgy

Chlup

Fintová

Hadraba

et al. 2019

Metals

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Correlating Strength and Hardness of High‐Entropy Alloys

Tian

et al. 2021

Adv Eng Mater

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Strength and hardness of metallic materials are reported to correlate in a specified form. Among various equations, yield strength is generally converted from Vickers hardness (HV) via a three‐time relation due to the simple and nondestructive nature of hardness testing. Herein, a through literature review is made and data of strength and HV for face‐centered cubic (FCC) and body‐centered cubic (BCC) high‐entropy alloys (HEA) are collected. The yield strength and HV visibly deviate from the three‐time relation, but the ultimate tensile strength and HV roughly follow the three‐time relation. New linear relationships, which are universally applied to convert HV to yield strength and ultimate tensile strength, are proposed.

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Near‐Threshold Fatigue Crack Propagation in Sintered 304L Stainless Steel Compact with Network Structure Composed of High‐Entropy CrMnFeCoNi Alloy

et al. 2023

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High‐entropy alloys (HEAs) have several superior mechanical properties. However, for these alloys, there is a trade‐off between tensile strength and fatigue‐crack propagation resistance, as is the case for materials with a homogeneous microstructure. The purpose of the present study is to achieve both high‐strength and fatigue‐crack propagation resistance by using a bimodal structure. CrMnFeCoNi alloy and AISI304L powders with different particles diameters are mixed and then consolidated using spark plasma sintering to fabricate sintered compacts with a network structure composed of coarse‐grained 304L surrounded by fine‐grained HEA microstructure. Stress intensity factor K‐decreasing tests are conducted at various force ratios in the ambient laboratory atmosphere to examine near‐threshold fatigue‐crack propagation in the sintered compacts. The ductility and threshold stress intensity range ΔKth tested at a high force ratio for the sintered compacts are higher than that for a homogeneous fine‐grained CrMnFeCoNi alloy. Fatigue cracks in the sintered compacts mainly propagate through the coarse‐grained 304L microstructure, which has high‐fatigue‐crack propagation resistance near the threshold. Therefore, ΔKth for the sintered compacts increases because the ΔKeff,th, which is derived from the 304L without degrading the tensile strength, is higher than that for homogeneous fine‐grained CrMnFeCoNi alloy.

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Fatigue behavior of CoCrFeMnNi high-entropy alloy under fully reversed cyclic deformation

Cited by 131 publications

References 42 publications

Fatigue Behaviour and Crack Initiation in CoCrFeNiMn High-Entropy Alloy Processed by Powder Metallurgy

Fatigue Behaviour and Crack Initiation in CoCrFeNiMn High-Entropy Alloy Processed by Powder Metallurgy

Correlating Strength and Hardness of High‐Entropy Alloys

Near‐Threshold Fatigue Crack Propagation in Sintered 304L Stainless Steel Compact with Network Structure Composed of High‐Entropy CrMnFeCoNi Alloy

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