Characterization of chemical short-range order in VCoNi medium-entropy alloy processed by spark plasma sintering

Cai, Weijin; He, Junyang; Wang, Li; Yang, Wenchao; Xu, Xiangqi; Yaqoob, Khurram; Wang, Zhangwei; Song, Min

doi:10.1016/j.scriptamat.2023.115463

Cited by 16 publications

(2 citation statements)

References 28 publications

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“…For example, the preference towards V-Co and V-Ni pairs and avoidance of V-V pairs formed in the VCoNi MEA after annealed [11]. Moreover, real-world alloys are usually processed or used at relatively low temperatures, where complex enthalpic interactions among various elements drive the formation of LCO or grain boundary segregations [2,24,[31][32][33].…”

Section: Origin Of Lco For Cunicofe Heamentioning

confidence: 99%

Impact of local chemical ordering on deformation mechanisms in single-crystalline CuNiCoFe high-entropy alloys: a molecular dynamics study

Shuang,

Liang,

Zhang

et al. 2023

Modelling Simul. Mater. Sci. Eng.

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High-entropy alloys (HEAs), composed of multiple constituent elements with concentrations ranging from 5% to 35%, have been considered ideal solid solution of multi-principal elements. However, recent experimental and computational studies have demonstrated that complex enthalpic interactions among constituents lead to a wide variety of local chemical ordering (LCO) at lower temperatures. HEAs containing Cu typically decompose by forming of Cu-rich phases during annealing, thus affecting mechanical properties. In this study, CuNiCoFe HEA was chosen as a model with a tendency for Cu segregation at low temperatures. The formation of LCO and its impact on the deformation behaviors in the single-crystalline CuNiCoFe HEA were studied via molecular dynamics simulations. Our results demonstrate that CuNiCoFe HEA decomposes by Cu clustering, in agreement with prior experimental and computational studies, owing to insufficient configuration entropy to compete against the mixing enthalpy at lower temperatures. A softening in ultimate stress in the LCO models was observed compared to the random solid solution models. The softening is due to the lower unstable stacking fault energy, which determines the nucleation event of dislocations, thereby rationalizing the dislocation nucleation in the Cu-rich regions and the softening of the overall ultimate strength in the LCO models. Additionally, the inhomogeneous FCC-BCC transformation is closely associated with concentration inhomogeneity. CuNiCoFe HEA with LCO can be regarded as composites, consisting of clusters with different properties. Consequently, concentration inhomogeneity induced by LCO profoundly impacts the mechanical properties and deformation behaviors of the HEA. This study provides insights into the effect of LCO on the mechanical properties of CuNiCoFe HEAs, which is crucial for developing HEAs with tailored properties for specific applications.

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Section: Origin Of Lco For Cunicofe Heamentioning

confidence: 99%

Impact of local chemical ordering on deformation mechanisms in single-crystalline CuNiCoFe high-entropy alloys: a molecular dynamics study

Shuang,

Liang,

Zhang

et al. 2023

Modelling Simul. Mater. Sci. Eng.

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“…However, it is challenging to experimentally detect and quantify CSRO, so the existence of conflicting data in the literature regarding the effect of CSRO on mechanical properties is understandable 4,5 . To directly show the presence of CSRO, various measurement methods have been employed including transmission electron microscopy (TEM) and X-ray diffraction (XRD) 5,[9][10][11][12][13][14] . Fewer studies have used other techniques such as Extended X-ray Absorption Fine Structure (EXAFS) 15 and Partial Pair Distribution Function (PDF) 15 .…”

mentioning

confidence: 99%

Comprehensive Analysis of Ordering in CoCrNi and CrNi2 Alloys

Coury,

Bacurau,

Moreira

et al. 2024

Preprint

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In the intricate realm of high and medium entropy alloys (HEAs/MEAs), the elusive nature of Chemical Short-Range Order (CSRO) has captivated researchers, creating intense debates on its impact on material properties. Rooted in the local arrangement of atoms, CSRO's pivotal role in shaping the structural and mechanical characteristics of HEAs remains a subject of fervent exploration. The challenges lie in confirming and quantifying CSRO, as its detection proves exceptionally demanding, contributing to conflicting data in the literature regarding its true effects on mechanical properties. Our work uses high-precision calorimetric data to unambiguously prove the existence and, coupled with atomistic simulations, quantify the type of CSRO. This methodology allows us to propose a mechanism for its formation and destruction based on the heat evolution during thermal analysis and facilitates a precise identification of local ordering in CoCrNi alloys. Samples of CoCrNi (Co33Cr33Ni33) and CrNi2 (Cr33Ni66) alloys are fabricated in varying ordered states, extensively characterized via synchrotron X-Ray diffraction, X-Ray absorption spectroscopy, and transmission electron microscopy. Samples with considerably different ordered states are submitted to tensile tests with in-situ synchrotron X-Ray diffraction. Despite inducing varied CSRO levels in CoCrNi, no significant alterations in overall mechanical behavior emerge. However, the CrNi2 alloy, which undergoes long-range ordering, experiences profound shifts in yield strength, ultimate tensile stress, dislocation density, and ductility. The novel methodology proposed in this work charts a course toward harnessing the nuanced effects of CSRO on material properties in complex alloys.

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Unveiling the Origin of the Strengthening Mechanism in a Novel Precious Metal Multi‐Principal Elements Alloy

Zhou,

Ge,

Xiong

et al. 2024

Advanced Science

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Precious metal electrical contact materials are pivotal in microelectronic devices due to their excellent chemical stability and electrical properties. Their practical application is hindered by the strength, contact resistance, and high cost. Multi‐principal elements alloys (MPEAs) provide the possibility to develop cost‐effective materials with enhanced mechanical properties. To address this, a novel precious metal MPEA, PdAgCuAuPtZn alloy, is designed, which exhibits significant solid solution strengthening and aging strengthening effects. The ultimate tensile strength increases from 747 MPa in the solution state to 1126 MPa in the aged state, while resistivity remains low. This study presents the first systematic investigation into the strengthening mechanisms of precious metal MPEAs using nanoindentation technology. These findings indicate that the aging strengthening of the alloy is attributed to spinodal decomposition (SD) and chemical short‐range order (CSRO) in the matrix. Furthermore, the precipitation structure with Cu‐rich and Ag‐rich phases gradually replaces the matrix, primarily accounting for aging softening. Additionally, it is discovered that precipitation structure can be strengthened by CSRO formed in the Cu‐rich phase, thus providing an innovative strengthening in PdAgCuAuPtZn alloy. These results will be beneficial to both deeply understanding the aging behaviors of PdAgCuAuPtZn alloys and designing high‐performance precious metal MPEAs.

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Characterization of chemical short-range order in VCoNi medium-entropy alloy processed by spark plasma sintering

Cited by 16 publications

References 28 publications

Impact of local chemical ordering on deformation mechanisms in single-crystalline CuNiCoFe high-entropy alloys: a molecular dynamics study

Impact of local chemical ordering on deformation mechanisms in single-crystalline CuNiCoFe high-entropy alloys: a molecular dynamics study

Comprehensive Analysis of Ordering in CoCrNi and CrNi2 Alloys

Unveiling the Origin of the Strengthening Mechanism in a Novel Precious Metal Multi‐Principal Elements Alloy

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