Simultaneously enhancing strength and ductility of a high-entropy alloy via gradient hierarchical microstructures

Hasan, Nazmul; Liu, Y.F.; An, X.H.; Gu, Ji; Song, Min; Cao, Yang; Li, Y.S.; Zhu, Yuntian; Liao, Xiaozhou

doi:10.1016/j.ijplas.2019.07.017

Cited by 225 publications

(29 citation statements)

References 71 publications

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“…The mechanical and conductive properties of Cu-Ti alloys can be simultaneously bolstered using the recently developed hierarchical reinforcement approach [ 14 , 15 , 16 , 17 , 18 ]. The hierarchical reinforcement can be achieved via the controlled condition-specific precipitation of primary and secondary phases at the micro- and nanoscale.…”

Section: Introductionmentioning

confidence: 99%

RETRACTED: Manufacturing of Conductive, Wear-Resistant Nanoreinforced Cu-Ti Alloys Using Partially Oxidized Electrolytic Copper Powder

et al. 2020

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Reactive powder composites Cu-(0–15%)TiH2 containing up to 5% native Cu2O were manufactured by high energy ball milling and then hot-pressed to produce bulk nanostructured copper–matrix alloys reinforced by Cu3Ti3O inclusions. Two high-energy ball-milling (HEBM) protocols were employed for the fabrication of Cu-Ti alloys: single-stage and two-stage ball milling, resulting in an order of magnitude refinement of TiH2 particles in the reactive mixtures. Single-stage HEBM processing led to the partial retention of Ti in the microstructure of hot-pressed specimens as the α-Ti phase and formation of fine-grained (100–200 nm) copper matrix interspersed with 5–20 nm Cu3Ti3O precipitates, whereas the two-stage HEBM led to the complete conversion of TiH2 into the Cu3Ti3O phase during the hot pressing but produced a coarser copper matrix (1–2 μm) with 0.1–0.2 μm wide polycrystalline Cu3Ti3O layers on the boundaries of Cu grains. The alloy produced using single-stage HEBM was characterized by the highest strength (up to 950 MPa) and electrical conductivity (2.6 × 107 Sm/m) as well as the lowest specific wear rate (1.1 × 10−5 mm3/N/m). The tribological performance of the alloy was enhanced by the formation of Cu3Ti3O microfibers in the wear debris, which reduced the friction coefficient against the Al2O3 counter-body. The potential applications of the developed alloys are briefly discussed.

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Section: Introductionmentioning

confidence: 99%

RETRACTED: Manufacturing of Conductive, Wear-Resistant Nanoreinforced Cu-Ti Alloys Using Partially Oxidized Electrolytic Copper Powder

et al. 2020

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“…Note that the regained strain hardening capability in the present NGL is different from the extra strain hardening accompanied by long-range internal stress development [27,32], because the latter originates from strain gradient-dependent geometrically necessary dislocation piling-up around zone (layer) boundaries [7,20,[24][25][26]48]. However, both of them in heterostructure are caused by the deformation incompatibility between heterogeneous zones.…”

Section: Articlesmentioning

confidence: 73%

Inter-zone constraint modifies the stress-strain response of the constituent layer in gradient structure

Wang

Zhu

et al. 2021

Sci. China Mater.

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How an individual constituent zone behaves during the deformation of a heterostructured metallic material is a fundamental issue for understanding heterostructure deformation, but it remains a challenge to experimentally observe it. Here we report a study on the stress-strain behavior of the nanostructured gradient layer (NGL) in an integrated gradient specimen that consists of a coarse-grained (CG) central layer sandwiched between two NGLs. Constraint from the CG central layer led to the formation of dense and dispersed stable strain bands (SBs) in the NGL, which regained dislocation hardening after initial recovery and grain coarsening. Consequently, the NGL exhibited a transient plateau of flow stress after yielding, and then regained extra strain hardening to achieve excellent uniform elongation. These unique behaviors are dramatically different from those of a freestanding NGL, indicating a fundamentally different deformation principle that is intrinsic to heterostructures, i.e., inter-zone constraint modifies the constitutive behavior of constituent zones.

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“…Details of the alloy preparation can be found in ref. 25 . Energy dispersive x-ray spectroscopy (EDS) elemental mapping was conducted in a Zeiss ® EVO 50 scanning electron microscope (SEM).…”

Section: Methodsmentioning

confidence: 99%

Effect of Ion Irradiation Introduced by Focused Ion-Beam Milling on the Mechanical Behaviour of Sub-Micron-Sized Samples

Liu

Niu

et al. 2020

Sci Rep

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The development of xenon plasma focused ion-beam (Xe + PFIB) milling technique enables sitespecific sample preparation with milling rates several times larger than the conventional gallium focused ion-beam (Ga + FIB) technique. As such, the effect of higher beam currents and the heavier ions utilized in the Xe + PFIB system is of particular importance when investigating material properties. To investigate potential artifacts resulting from these new parameters, a comparative study is performed on transmission electron microscopy (TEM) samples prepared via Xe + PFIB and Ga + FIB systems. Utilizing samples prepared with each system, the mechanical properties of CrMnFeCoNi high-entropy alloy (HEA) samples are evaluated with in situ tensile straining TEM studies. The results show that HEA samples prepared by Xe + PFIB present better ductility but lower strength than those prepared by Ga + FIB. This is due to the small ion-irradiated volumes and the insignificant alloying effect brought by Xe irradiation. Overall, these results demonstrate that Xe + PFIB systems allow for a more efficient material removal rate while imparting less damage to HEAs than conventional Ga + FIB systems. The rapid development of micro-electromechanical systems (MEMS) and nano-electromechanical systems (NEMS), which utilize materials at the micron scale and below, has resulted in a growing number of potential applications in electronic devices 1. Mechanical properties are of particular importance for applications in M/NEMS as efforts seek to improve the functionality and reliability of advanced electronic devices. Continuing efforts have focused on understanding how the mechanical properties of these materials change with decreasing dimensions 2-6. To facilitate this understanding, in situ straining transmission electron microscopy (TEM) is commonly used to test the mechanical properties 7-10 and observe deformation mechanisms 11-17 of small-sized samples. In situ straining TEM allows for simultaneous structural characterisation and mechanical property testing 13,15,18 , providing opportunities for building direct relationships between microstructure, deformation mechanisms, and mechanical properties of small-sized materials. Sample preparation is of particular importance when studying small-sized materials in the TEM 19. Traditionally, these TEM samples are prepared using a focused ion-beam (FIB) with a gallium ion (Ga +) source to thin samples from bulk to ~100 nm 20-26. Despite technological advances, the material removal rates of Ga + FIB systems have remained too low for researchers hoping to increase sample preparation efficiency 27. To help facilitate more efficient sample preparation, researchers have developed FIB systems with alternative ion sources such as the Xe + plasma FIB (Xe + PFIB) 27. As an alternative to Ga + ions, Xe + PFIB systems utilize inert Xe gas as the milling media resulting in material removal rates around six times larger than for Ga + mills 27 , which enables the preparation of samples with larger dimensions. On...

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Simultaneously enhancing strength and ductility of a high-entropy alloy via gradient hierarchical microstructures

Cited by 225 publications

References 71 publications

RETRACTED: Manufacturing of Conductive, Wear-Resistant Nanoreinforced Cu-Ti Alloys Using Partially Oxidized Electrolytic Copper Powder

RETRACTED: Manufacturing of Conductive, Wear-Resistant Nanoreinforced Cu-Ti Alloys Using Partially Oxidized Electrolytic Copper Powder

Inter-zone constraint modifies the stress-strain response of the constituent layer in gradient structure

Effect of Ion Irradiation Introduced by Focused Ion-Beam Milling on the Mechanical Behaviour of Sub-Micron-Sized Samples

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