The present work investigated the formation and mechanical behavior of body-centered-cubic (BCC) Zr(Hf)-Nb-Ti medium entropy alloys (MEAs), in which three series of alloys, [Zr-Zr14](Zr,Nb)3, [Ti-Zr14](Ti,Nb)3, and [Ti-(Hf,Zr)14](Nb)3, were designed by the cluster formula approach. With increasing the Nb content, the BCC-β structural stability of the [Zr-Zr14](Zr,Nb)3 alloys would be enhanced, as evidenced by the BCC [Zr-Zr14](Nb)3 (Zr83.33Nb16.67 in atomic percent at. pct) alloy containing a minor amount of ω phase. An appropriate content of Ti addition can further improve the BCC-β stability of [Ti-Zr14](Nb3) (Zr77.77Ti5.56Nb16.67) alloy without any ω precipitation. The further substitution of Hf/Ti for the Zr could also render the [Ti-Zr8Hf4Ti2](Nb3) (Zr44.44 Hf22.22Ti16.67Nb16.67) alloy with a single BCC structure. All these BCC MEAs exhibit prominent mechanical properties, as exemplified by the [Ti-Zr8Hf6](Nb3) (Zr44.44Hf33.33Ti5.56Nb16.67) with a higher yield strength of 662 MPa, a larger elongation to fraction of 15.2 pct, and a lower Young’s modulus of 71 GPa.
#1Yue Ma(DUT: Dalian University of Technology)H-Index: 7
#2Qing Wang(DUT: Dalian University of Technology)H-Index: 9
Last. T.G. Nieh(UT: University of Tennessee)H-Index: 86
view all 8 authors...
Multiprincipal-element alloys (MPEAs), including high-entropy alloys, are a new class of materials whose thermodynamical properties are mainly driven by configuration entropy, rather than enthalpy in the traditional alloys, especially at high temperatures. Herein, the design of a novel soft-magnetic nonequiatomic, quaternary MPEA is described, via tuning its chemical composition to deliberately manipulate its microstructure, such that it contains ultrafine ferromagnetic body-centered-cubic (BCC)...
Abstract The present work developed a new body-centered-cubic (BCC)-based Al0.4Nb0.5Ta0.5TiZr0.8 refractory high entropy alloy with coherent precipitation. The formation of cuboidal nanoprecipitates with a size of 25~50 nm in an 873 K-aged alloy is ascribed to a moderate lattice misfit. A Zr5Al3 phase also coexists with B2 in a same particle shape due to similar chemical compositions, in which Ti is enriched in B2 but not in Zr5Al3. The BCC/B2 coherency would be deteriorated with increasing the ...
#1Damian Sobieraj(UKAEA: United Kingdom Atomic Energy Authority)
#1Damian Sobieraj(UKAEA: United Kingdom Atomic Energy Authority)H-Index: 4
Last. Duc Nguyen-Manh(UKAEA: United Kingdom Atomic Energy Authority)H-Index: 9
view all 8 authors...
The development of high-entropy alloys (HEAs) focuses on exploring compositional regions in multi-component systems with all alloy elements in equal or near-equal atomic concentrations. Initially it was based on the main idea that high mixing configurational entropy contributions to the alloy free energy could promote the formation of a single solid solution phase. By using the ab-initio based Cluster Expansion (CE) Hamiltonian model constructed for the quinary bcc Cr-Ta-Ti-V-W system in combina...
Abstract Complex, concentrated alloys (CCAs) containing refractory principal elements and Al can have microstructures with disordered body-centered cubic (BCC) and ordered B2 phases that are remarkably similar to superalloys. The simple idea of copying superalloy microstructures in these BCC-based refractory alloys introduces a set of audacious challenges. BCC metals and B2 compounds are often brittle at room temperature; the B2 phase is unstable in refractory-Al binaries and reasons for its sta...
Last. Andrew M. Minor(NCEM: National Center for Electron Microscopy)H-Index: 1
view all 9 authors...
Traditional metallic alloys are mixtures of elements where the atoms of minority species tend to distribute randomly if they are below their solubility limit, or lead to the formation of secondary phases if they are above it. Recently, the concept of medium/high entropy alloys (MEA/HEA) has expanded this view, as these materials are single-phase solid solutions of generally equiatomic mixtures of metallic elements that have been shown to display enhanced mechanical properties. However, the quest...
#1Easo P George(UT: University of Tennessee)H-Index: 73
#2William A. Curtin(EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 79
Last. Cemal Cem Tasan(MIT: Massachusetts Institute of Technology)H-Index: 37
view all 3 authors...
Abstract The high-entropy alloy (HEA) concept was based on the idea that high mixing entropy can promote formation of stable single-phase microstructures. During the past 15 years, various alloy systems have been explored to identify HEA systems with improved property combinations, leading to an extraordinary growth of this field. In the large pool of alloys with varying characteristics, the first single-phase HEA with good tensile properties, the equiatomic CrMnFeCoNi alloy has become the bench...
#1Xue-Hui Yan(USTB: University of Science and Technology Beijing)H-Index: 7
#2Yong Zhang(USTB: University of Science and Technology Beijing)H-Index: 112
Abstract The center of phase diagram, relatively high-disordered region, often has few alloy systems available, especially for traditional ternary alloy systems. Here, we develop a novel Zr50Ti35Nb15 alloy near the center of phase diagram, as a body-centered cubic (bcc) solid solution phase, which displays a unique combination of Young's modulus of 62 GPa, yield strength of 657 MPa, tensile ductility of 21.9%, and excellent corrosion resistance (Ecorr=422 mV, Ipit=0.336 µA/cm2). The excellent me...
#1Vishal Soni(UNT: University of North Texas)H-Index: 15
#2B. Gwalani(PNNL: Pacific Northwest National Laboratory)H-Index: 1
Last. Robi Banerjee(UNT: University of North Texas)H-Index: 56
view all 8 authors...
Abstract A phenomenon of “phase inversion”, presumably the first ever experimental evidence in metallic alloys, is shown in a refractory high entropy alloy (RHEA), Al0.5NbTa0.8Ti1.5V0.2Zr. Phase inversion in crystalline solid systems is driven by the differences in elastic modulus of the two phases. Quenching from a high temperature single phase field, the RHEA exhibits a co-continuous mixture of a disordered BCC and an ordered B2 phase, that upon isothermal annealing at 600°C develops via spino...
Last. Andrew M. Minor(LBNL: Lawrence Berkeley National Laboratory)H-Index: 64
view all 9 authors...
Traditional metallic alloys are mixtures of elements where the atoms of minority species tend to distribute randomly if they are below their solubility limit, or lead to the formation of secondary phases if they are above it. Recently, the concept of medium/high entropy alloys (MEA/HEA) has expanded this view, as these materials are single-phase solid solutions of generally equiatomic mixtures of metallic elements that have been shown to display enhanced mechanical properties. However, the quest...
Abstract The mechanical properties and microstructure evolution of a precipitation-strengthened refractory high-entropy alloy, HfNbTaTiZr, with equiaxed grains are reported. The as-cast alloy shows a high yield strength of 356 MPa at 1200 °C, and 1597 MPa with good ductility at room temperature. The enhancement in strength is attributed to precipitation strengthening. Afterwards, microstructure evolution was investigated under several annealing treatment conditions: 1000 °C for 24 h, 1200 °C for...