Compositional effect on microstructure and properties of NbTiZr-based complex concentrated alloys

Senkov, O.N.; Rao, Satish I.; Chaput, K.J.; Woodward, C.

doi:10.1016/j.actamat.2018.03.065

Cited by 156 publications

(42 citation statements)

References 27 publications

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“…6(A-C)), with no second-phase observed even at higher magnifications. This is in contrast to previous reports of the equiatomic NbTiVZr HEA [26,62]. The absence of these features in the current study is attributed to the rapid cooling rate employed (~100 K s -1 ) compared to the previous studies (~10 K min -1 ).…”

Section: As-cast and Homogenised Microstructurescontrasting

confidence: 99%

High temperature, low neutron cross-section high-entropy alloys in the Nb-Ti-V-Zr system

et al. 2019

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High-entropy alloys (HEAs) with high melting points and low thermal neutron cross-section are promising new cladding materials for generation III+ and IV power reactors. In this study a recently developed high throughput computational screening tool Alloy Search and Predict (ASAP) has been used to identify the most likely candidate single-phase HEAs with low thermal neutron cross-section, from over a million four-element equimolar combinations. The selected NbTiVZr HEA was further studied by density functional theory (DFT) for moduli and lattice parameter, and by CALPHAD to predict phase formation with temperature. HEAs of NbTiVZrx (x = 0.5, 1, 2) were produced experimentally, with Zr varied as the dominant cross-section modifier. Contrary to previous experimental work, these HEAs were demonstrated to constitute a single-phase HEA system; a result obtained using a faster cooling rate following annealing at 1200°C. However, the beta (BCC) matrix decomposed following aging at 700°C, into a combination of nano-scale beta, alpha (HCP) and C15 Laves phases.

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Section: As-cast and Homogenised Microstructurescontrasting

confidence: 99%

High temperature, low neutron cross-section high-entropy alloys in the Nb-Ti-V-Zr system

et al. 2019

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“…will be introduced during the preparing process, which will lead to the formation of precipitated phases [4,8,9]. In fact, several recent studies have revealed that in many cases, dual-phase microstructures can be observed in some HEAs [10,11] and the second phase significantly enhances the strength of HEAs by precipitation strengthening [12,13,14,15,16,17]. Therefore, the precipitated phase, caused by introduction of interstitial elements, may benefit the mechanical properties of HEAs in some cases.…”

Section: Introductionmentioning

confidence: 99%

Enhanced Strength of a Mechanical Alloyed NbMoTaWVTi Refractory High Entropy Alloy

Long

Zhang

et al. 2018

Materials

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A NbMoTaWVTi refractory high entropy alloy (HEA) has been successfully synthesized by mechanical alloying (MA) and spark plasma sintering (SPS). The microstructure and mechanical properties of this alloy are investigated. It is observed that only two types of body-centered cubic (BCC) solid solutions are formed in the powders after ball milling for 40 h. However, a new face-centered cubic (FCC) precipitated phase is observed in the BCC matrix of bulk material consolidated by SPS. The FCC precipitated phase is identified as TiO, due to the introduction of O during the preparing process of HEA. The compressive yield strength, fracture strength, and total fracture strain of the consolidated bulk HEA are 2709 MPa, 3115 MPa, and 11.4%, respectively. The excellent mechanical properties can be attributed to solid solution strengthening and grain boundary strengthening of the fine-grained BCC matrix, as well as the precipitation strengthening owing to the formation of TiO particles.

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“…Then we produced also other 3 element combinations containing Ti, namely TaTiZr and NbTaTi. Based on the observed results; 4 element alloys containing Ti and Ta with different Nb to Zr ratio were produced as well to explore the influence of chemical composition on elongation.NbTaTiZr [14] and NbTiZr [20,21] studies have already been reported. No reports about TaTiZr and NbTaTi were found in literature.One can notice that set of the produced element combinations is not complete.…”

mentioning

confidence: 95%

“…NbTaTiZr [14] and NbTiZr [20,21] studies have already been reported. No reports about TaTiZr and NbTaTi were found in literature.…”

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confidence: 95%

Microstructure and Room Temperature Mechanical Properties of Different 3 and 4 Element Medium Entropy Alloys from HfNbTaTiZr System

Zýka

Málek

Veselý

et al. 2019

Entropy

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Refractory high entropy alloys (HEA) are promising materials for high temperature applications. This work presents investigations of the room temperature tensile mechanical properties of selected 3 and 4 elements medium entropy alloys (MEA) derived from the HfNbTaTiZr system. Tensile testing was combined with fractographic and microstructure analysis, using scanning electron microscope (SEM), wavelength dispersive spectroscope (WDS) and X-Ray powder diffraction (XRD). The 5 element HEA alloy HfNbTaTiZr exhibits the best combination of strength and elongation while 4 and 3 element MEAs have lower strength. Some of them are ductile, some of them brittle, depending on microstructure. Simultaneous presence of Ta and Zr in the alloy resulted in a significant reduction of ductility caused by reduction of the BCC phase content. Precipitation of Ta rich particles on grain boundaries reduces further the maximum elongation to failure down to zero values.Entropy 2019, 21, 114 2 of 17 Different elements are used to fabricate HEAs. Although the number of possible 4 or 5 elements combinations is enormous five basic metallic HEA groups can be distinguished: FCC HEAs based on the Cantor alloy, BCC refractory metal HEAs, light element HEAs, HCP HEAs and precious functional HEAs [7]. Ceramic HEAs have been established as well [8,9].Our attention was attracted by the refractory HEA group, which is composed of elements from IV, V and VI groups of the periodic table of elements [10]. These elements are characterized by prevailing good mutual miscibility and high melting points. The melting point of titanium (1668 • C) is the lowest among them. Therefore HEAs composed of these elements are intended for high temperature applications. Moreover some of these elements are biocompatible [11]. Therefore some of these alloys can be attractive for bioimplant related materials research. Note that β-Ti alloys used in bioimplant research are usually composed of this group of elements [12]. Several biocompatible HEAs have been already studied [13][14][15][16]. Also, hard ceramic composites were produced from the metals from IV, V and VI groups of the periodic table [17].Original definition of HEAs with single phase solid solution microstructure and good room temperature mechanical properties, especially ductility, is beneficial also for use in human medicine. Inspiration can be found also in other materials used for production of bioimplants which are used or have been used in other parts of material research, for example, TiAl6V4 in aerospace, CoCrMo in aero engines.Our first attempt in research of HEAs was therefore related to HfNbTaTiZr refractory metal alloy [18]. Our research was inspired by Senkov [19] and confirmed our expectations. Ingots produced by vacuum arc melting possessed single phase solid solution microstructure, with a high room temperature tensile strength and ductility.Some of the elements used in the HfNbTaTiZr alloy are very similar to each other with very similar chemical behaviour; Nb is chemically similar to Ta and Zr to ...

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Compositional effect on microstructure and properties of NbTiZr-based complex concentrated alloys

Cited by 156 publications

References 27 publications

High temperature, low neutron cross-section high-entropy alloys in the Nb-Ti-V-Zr system

High temperature, low neutron cross-section high-entropy alloys in the Nb-Ti-V-Zr system

Enhanced Strength of a Mechanical Alloyed NbMoTaWVTi Refractory High Entropy Alloy

Microstructure and Room Temperature Mechanical Properties of Different 3 and 4 Element Medium Entropy Alloys from HfNbTaTiZr System

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