Enhancement of strength-ductility balance of heavy Ti and Al alloyed FeCoNiCr high-entropy alloys via boron doping

Qi, Yongliang; Cao, Tinghui; Zong, Hongxiang; Wu, Yake; Lin, He; Ding, Xiangdong; Jiang, F.; Jin, Shenbao; Sha, Gang; Sun, Jun

doi:10.1016/j.jmst.2020.10.023

Cited by 52 publications

(8 citation statements)

References 36 publications

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“…Carefully tuning these parameters enables control over the ductility. Point defects, dislocations and other microstructure effects will also affect the ductility of the system [33][34][35][36][37][38], but are out of the scope of this work.…”

Section: Discussionmentioning

confidence: 99%

Nonlinear deformation and elasticity of BCC refractory metals and alloys

Raghuraman¹,

Widom²,

Gao³

2022

Preprint

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Application of isotropic pressure or uniaxial strain alters the elastic properties of materials; sufficiently large strains can drive structural transformations. Linear elasticity describes stability against infinitesimal strains, while nonlinear elasticity describes the response to finite deformations.It was previously shown that uniaxial strain along [100] drives refractory metals and alloys towards mechanical instabilities. These include an extensional instability, and a symmetry-breaking orthorhombic distortion caused by a Jahn-Teller-Peierls instability that splays the cubic lattice vectors. Here, we analyze these transitions in depth. Eigenvalues and eigenvectors of the Wallace tensor identify and classify linear instabilities in the presence of strain. We show that both instabilities are discontinuous, leading to discrete jumps in the lattice parameters. We provide physical intuition for the instabilities by analyzing the changes in first principles energy, stress, bond lengths and angles upon application of strain. Electronic band structure calculations show differential occupation of bonding and anti-bonding orbitals, driven by the changing bond lengths and leading to the structural transformations. Strain thresholds for these instabilities depend on the valence electron count.

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Section: Discussionmentioning

confidence: 99%

Nonlinear deformation and elasticity of BCC refractory metals and alloys

Raghuraman¹,

Widom²,

Gao³

2022

Preprint

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“…First, B has the effect of strengthening the grain boundary of the Ni 3 Al-type ordered phase, which can effectively overcome room temperature brittleness and change the fracture mode at ambient temperature from intergranular to transgranular fracture. [29][30][31] Second, the extremely negative mixing enthalpy of B and Ti offset the high mixing entropy of the system, and the excess Ti tends to enrich the grain boundary to form Ti-B intermetallic compounds, which increase alloy strength considerably. According to this, we optimized Ni 35 Co 35 Fe 10 Al 8 Ti 10 B 2 (hereinafter referred to as ATB2).…”

Section: Ingredient Design Using Calphadmentioning

confidence: 99%

“…It is agreed that the addition of B can increase the bonding force of the grain boundary, effectively strengthen the grain boundary, and alleviate the stress caused by the difference in concentration between the precipitate and the matrix, which in turn improves cracks and micropores, thereby effectively improving the ductility of the alloy. [30,65] At the same time, borides generally exist in granular form at the grain boundaries, effectively hindering the grain boundary slip and the connection and expansion of grain boundary micropores. Therefore, it is obvious that ATB2 can maintain a ductility in excess of 20% while possessing an ultrahigh strength of nearly 2 GPa, which is closely related to the doping of boron.…”

Section: Deformation Mechanismsmentioning

confidence: 99%

Ultrastrong High‐Ductility Ni₃₅Co₃₅Fe₁₀Al₁₀Ti₈B₂ High‐Entropy Alloy Strengthened with Super‐High Concentration L1₂ Precipitates

Zhu

Wang

et al. 2023

Adv Eng Mater

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L12 phase hardening alloys with excellent mechanical properties are of great significance for structural applications. However, low volume fractions of L12 precipitates in conventional alloys (nearly lower than 60%) tend to limit their practical usage, while the strengths of the alloys generally increase with L12 precipitation contents. Herein, a novel high‐entropy alloy (HEA) Ni35Co35Fe10Al8Ti10B2 with ultrahigh concentration L12 precipitates is successfully designed aided by the calculation of phase diagrams (CALPHAD). The volume fraction of L12 precipitates in this HEA is up to 75% and outperforms that of most of traditional superalloys. The novel L12‐strengthened Ni35Co35Fe10Al8Ti10B2 has an ultrahigh tensile yield strength of ≈1.45 GPa, ultimate tensile strength of ≈1.9 GPa, and great ductility of ≈23% at room temperature. The desirable strength–ductility combination is superior to most of conventional superalloys and reported HEAs, mainly due to the presence of ultrahigh concentration L12 precipitates that act as dislocation obstacles and the formation of numerous stacking faults and deformation twining. This work is expected to provide guidance for developing new high‐performance HEAs with an excellent combination of strength and ductility.

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“…The addition of B element can effectively reduce the number of voids formed between the second phase particles and the alloy matrix, as seen in Figure 1(a-d) and Figure 4(f). Therefore, B addition helped enhance the bonding between different phases, reducing the stress concentration and crack formation that improved ductility [19].…”

Section: Mechanical Propertiesmentioning

confidence: 99%

Effect of Ti and B additions on the microstructure and properties of FeCoCrNi high entropy alloys prepared by hot pressing

et al. 2022

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FeCoCrNi) 100-3x Ti x B 2x (x = 0, 1, 2 and 6 at.-%) high entropy alloys (HEAs) were fabricated by hot pressing. The effects of Ti and B content on the microstructure and mechanical properties were investigated using X-ray electron diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). The results show that the FeCoCrNi highentropy alloy form single FCC phase. With the increase of Ti and B content, dual FCC phases appeared in the alloys. Additionally, the per cent elongation of alloys first increased and then declined, while the ultimate tensile strength kept moving up. The (FeCoCrNi) 97 TiB 2 alloy has the highest per cent elongation of 13.1%, which is more than three times that of the FeCoCrNi. the (FeCoCrNi) 82 Ti 6 B 12 alloy shows the highest ultimate tensile strength, which is 646.5 ± 0.1 MPa. The enhanced strength is attributed to solid solution effect and Orowan process.

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Enhancement of strength-ductility balance of heavy Ti and Al alloyed FeCoNiCr high-entropy alloys via boron doping

Cited by 52 publications

References 36 publications

Nonlinear deformation and elasticity of BCC refractory metals and alloys

Nonlinear deformation and elasticity of BCC refractory metals and alloys

Ultrastrong High‐Ductility Ni₃₅Co₃₅Fe₁₀Al₁₀Ti₈B₂ High‐Entropy Alloy Strengthened with Super‐High Concentration L1₂ Precipitates

Effect of Ti and B additions on the microstructure and properties of FeCoCrNi high entropy alloys prepared by hot pressing

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Enhancement of strength-ductility balance of heavy Ti and Al alloyed FeCoNiCr high-entropy alloys via boron doping

Cited by 52 publications

References 36 publications

Nonlinear deformation and elasticity of BCC refractory metals and alloys

Nonlinear deformation and elasticity of BCC refractory metals and alloys

Ultrastrong High‐Ductility Ni35Co35Fe10Al10Ti8B2 High‐Entropy Alloy Strengthened with Super‐High Concentration L12 Precipitates

Effect of Ti and B additions on the microstructure and properties of FeCoCrNi high entropy alloys prepared by hot pressing

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Ultrastrong High‐Ductility Ni₃₅Co₃₅Fe₁₀Al₁₀Ti₈B₂ High‐Entropy Alloy Strengthened with Super‐High Concentration L1₂ Precipitates