Ultrastrong and ductile (CoCrNi)94Ti3Al3 medium-entropy alloys via introducing multi-scale heterogeneous structures

Zou, Jianpeng; Yang, Hailin; Dong, Xiucheng; Cao, Peng; Liao, Xiaozhou; Liu, Zhilin; Ji, Shouxun

doi:10.1016/j.jmst.2022.06.048

Cited by 43 publications

(4 citation statements)

References 77 publications

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“…The corresponding maps and calculated distribution of GNDs along the arrow direction are described in figures 11(b)-(f). Notably, the GNDs density (ρ) can be calculated using strain gradient theory as follows [50]:…”

Section: Deformation Mechanisms Of Lpbf-printed Pure Zn Materialsmentioning

confidence: 99%

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Role of heterogenous microstructure and deformation behavior in achieving superior strength-ductility synergy in zinc fabricated via laser powder bed fusion

Dong,

Han,

Zhao

et al. 2024

Int. J. Extrem. Manuf.

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Zinc (Zn) is considered a promising biodegradable metal for implant applications due to its appropriate degradability and favorable osteogenesis properties. In this work, laser powder bed fusion (LPBF) additive manufacturing was employed to fabricate pure Zn with a heterogenous microstructure and exceptional strength-ductility synergy. An optimized processing window of LPBF was established for printing Zn samples with relative densities greater than 99% using a laser power range of 80–90 W and a scanning speed of 900 mm/s. The Zn sample printed with a power of 80 W at a speed of 900 mm/s exhibited a hierarchical heterogenous microstructure consisting of millimeter-scale molten pool boundaries, micrometer-scale bimodal grains, and nanometer-scale pre-existing dislocations, due to rapid cooling rates and significant thermal gradients formed in the molten pools. The printed sample exhibited the highest ductility of ~12.1% among all reported LPBF-printed pure Zn to date with appreciable ultimate tensile strength (~128.7 MPa). Such superior strength-ductility synergy can be attributed to the presence of multiple deformation mechanisms that are primarily governed by heterogeneous deformation-induced hardening resulting from the alternatively arrangement of bimodal Zn grains with pre-existing dislocations. Additionally, continuous strain hardening was facilitated through the interactions between deformation twins, grains and dislocations as strain accumulated, further contributing to the superior strength-ductility synergy. These findings provide valuable insights into the deformation behavior and mechanisms underlying exceptional mechanical properties of LPBF-printed Zn and its alloys for implant applications.

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Section: Deformation Mechanisms Of Lpbf-printed Pure Zn Materialsmentioning

confidence: 99%

“…Plastic deformation in most crystalline materials highly depends on dislocation strengthening, which primarily arises from interactions between pre-existing and mobile dislocations during plastic deformation. As per the Bailey-Hirsch formula, ∆σ DS can be mathematically expressed as [50]:…”

Section: Strengthening Mechanismsmentioning

confidence: 99%

Role of heterogenous microstructure and deformation behavior in achieving superior strength-ductility synergy in zinc fabricated via laser powder bed fusion

Dong,

Han,

Zhao

et al. 2024

Int. J. Extrem. Manuf.

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show abstract

“…[6][7][8][9][10] These elements can be introduced into HEAs to form more pinning sites for dislocation motions, improving their mechanical properties. [11,12] However, a high addition of these elements can form brittle precipitates inside the matrix, significantly reducing the ductility of MEAs and HEAs. [6,10] Although L1 2 -Ni 3 (Al, Ti) precipitates offer a method to strengthen MEAs, introducing Al/Ti into MEAs brings about some brittle phases.…”

Section: Introductionmentioning

confidence: 99%

“…[8,9] Due to the existence of deformation twinning (DT) and stacking faults (SFs), most face-centered cubic (FCC) MEAs with low SFs exhibit excellent ductility. [12,13] Therefore, the FCC MEAs with low SFs are potential alloys that can be modified by introducing heterogeneous grain structures (HGS) and precipitations to enhance their strength and ductility. [14,15] For example, the inclusion of a trace of Al and Ti results in an HGS with an L1 2 structure and heterogeneous precipitation, with a high strength surpassing 2 GPa and an average elongation at a rate of 13%.…”

Section: Introductionmentioning

confidence: 99%

Strengthening and Toughening of the Co₃₄Cr₃₂Ni₂₇Al_3.5Ti_3.5 Alloy Through Coherent L1₂ Nanoprecipitates

Li,

Song,

Gao

et al. 2024

Adv Eng Mater

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In this work, the L12‐strengthened Co34Cr32Ni27Al3.5Ti3.5 medium‐entropy alloy (MEA) with outstanding strength and ductility was developed through cold rolling and annealing (CRA). The CRA promotes the formation of coherent L12 nanoprecipitates in the matrix and precipitates inside the grains (Ti‐rich phases), resulting in dislocation sliding and multiplication during deformation. The as‐cast sample exhibits low yield strength (YS) of ∽498.5 MPa, ultimate tensile strength (UTS) of ∽820.5 MPa, and uniform elongation (UE) of ∽29.8%. After cold rolling and annealing, the YS, UTS, and UE are significantly increased to ∽678.4 MPa, ∽1109.3 MPa, and ∽44.5%, respectively. The excellent mechanical performance results from dislocation strengthening and precipitation strengthening of the L12 phase. The trade‐off of strength‐ductility is resolved by achieving an appropriate balance between the hard phase rich in L12/Ti and the soft FCC phase. Our finding demonstrates that the CRA method can be used to create coherent L12 nanoprecipitates that are beneficial for strong and ductile MEA. This work provides a broader perspective for CoCrNi‐based MEAs with high performance in the future.This article is protected by copyright. All rights reserved.

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Effects of Cold‐Rolling and Subsequent Annealing on Microstructure and Mechanical Properties of (CrCoNi)₉₇Al_1.5Ti_1.5 Medium‐Entropy Alloy

Zhong,

Liu,

Zhang

et al. 2024

Adv Eng Mater

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In this study, the (CrCoNi)97Al1.5Ti1.5 medium‐entropy alloy (MEA) is prepared and subjected to cold‐rolling and annealing. The phase and microstructure are characterized by using X‐ray diffraction (XRD), backscattered electron imaging (BSEI), electron backscattered diffraction (EBSD), and transmission Kikuchi diffraction (TKD). Microhardness and tensile properties of the deformed and annealed samples are measured. The results show that a large amount of lamellar dislocation substructures (LDS) is formed during cold‐rolling up to 50% reduction. After a 50% rolling reduction and annealing at 600 °C for 1 h, the LDS inside the deformed grains does not change significantly. When the annealing temperature increases to 650 °C, a large amount of LDS begins to disappear and is replaced by recrystallized grains and high‐density annealing twins. When the annealing temperature reaches 700 °C, a completely recrystallized structure is obtained. Cold‐rolling deformation leads to a linear increase in the microhardness and tensile strength of MEA. The 50% reduction sample will harden again after short‐time annealing at 600 °C while softening will occur after annealing at 650 °C or 700 °C. The deformation mechanisms and strengthening mechanisms are also discussed and analyzed.

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Ultrastrong and ductile (CoCrNi)94Ti3Al3 medium-entropy alloys via introducing multi-scale heterogeneous structures

Cited by 43 publications

References 77 publications

Role of heterogenous microstructure and deformation behavior in achieving superior strength-ductility synergy in zinc fabricated via laser powder bed fusion

Role of heterogenous microstructure and deformation behavior in achieving superior strength-ductility synergy in zinc fabricated via laser powder bed fusion

Strengthening and Toughening of the Co₃₄Cr₃₂Ni₂₇Al_3.5Ti_3.5 Alloy Through Coherent L1₂ Nanoprecipitates

Effects of Cold‐Rolling and Subsequent Annealing on Microstructure and Mechanical Properties of (CrCoNi)₉₇Al_1.5Ti_1.5 Medium‐Entropy Alloy

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Ultrastrong and ductile (CoCrNi)94Ti3Al3 medium-entropy alloys via introducing multi-scale heterogeneous structures

Cited by 43 publications

References 77 publications

Role of heterogenous microstructure and deformation behavior in achieving superior strength-ductility synergy in zinc fabricated via laser powder bed fusion

Role of heterogenous microstructure and deformation behavior in achieving superior strength-ductility synergy in zinc fabricated via laser powder bed fusion

Strengthening and Toughening of the Co34Cr32Ni27Al3.5Ti3.5 Alloy Through Coherent L12 Nanoprecipitates

Effects of Cold‐Rolling and Subsequent Annealing on Microstructure and Mechanical Properties of (CrCoNi)97Al1.5Ti1.5 Medium‐Entropy Alloy

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Product

Resources

About

Strengthening and Toughening of the Co₃₄Cr₃₂Ni₂₇Al_3.5Ti_3.5 Alloy Through Coherent L1₂ Nanoprecipitates

Effects of Cold‐Rolling and Subsequent Annealing on Microstructure and Mechanical Properties of (CrCoNi)₉₇Al_1.5Ti_1.5 Medium‐Entropy Alloy