Laser beam welding of a low density refractory high entropy alloy

In particular,the effect of different pre-heating temperatures was examined. Due to the low ductility of the material, laser beam welding at room temperature resulted in the formations of hot cracks. Sound butt joints without cracks were produced using pre-heating to T≥600 ◦C. In the initial as-cast condition, the alloy consisted of coarse bcc grains with a small amount of lens-shaped C15 Laves phase particle

Structure and mechanical properties of near-eutectic refractory Al-Cr-Nb-Ti-Zr high entropy alloys

In this study, the structure and mechanical properties of the near-eutectic refractory Al₂₄Cr₁₁Nb₁₁Ti₃₇Zr₁₇, Al₂₀Cr₂₀Nb₂₅Ti₂₅Zr₁₁₀, and Al₂₈Cr₁₅Nb₁₅₅Ti₂₀Zr₂₂ (at.%) high entropy alloys were investigated. Both the Al₂₄Cr₁₁₁Nb₁₁Ti₃₇₇Zr₁₇ and Al₂₀Cr₂₀Nb₂₅Ti₂₂₅Zr₁₀₀ alloys had a hypoeutectic structure, while the Al₂₈Cr₁₅Nb₁₅Ti₂₀Zr₂₂ alloy had a hypereutectic one. The proeutectic phase in the Al₂₄Cr₁₁Nb₁₁Ti₃₇Zr₁₇ and Al₂₀Cr₂₀Nb₂₅Ti₂₅Zr₁₀ alloys was the ordered B2 phase and in the Al₂₈Cr₁₅Nb₁₅Ti₂₀Zr₂₂ alloy - the C14 Laves phase. In all three alloys, the eutectic regions possessed a fine lamellar structure composed of a mixture of the C14 Laves and B2 phases. The densities of the alloys were 5.20-5.89 g/cm

Design and characterization of eutectic refractory high entropy alloys

Eutectic alloys are natural in-situ composites with near-equilibrium structures, impressive strength-ductility trade- off, and perfect castability. In the current study, novel eutectic Al-Cr-Nb-Ti-Zr refractory high entropy alloys (RHEAs) were designed using a CALPHAD (CALculation of PHAse Diagrams) approac

Aging behavior of two refractory Ti-Nb-(Hf, Zr)-Al high entropy alloys

In the present work, structure and mechanical properties of the Ti₄₀Nb₃₀Hf₁₅Al15 and Ti₄₀Nb₃₀Zr₂₀Al₁₀ refractory high entropy alloys after cold rolling to 80% reduction, recrystallization annealing at 900 °C for 15 min, and further aging treatment at T = 500, 600 and 700 °C for 1-96 h were studie

Precipitation-hardened refractoryTi-Nb-Hf-Al-Ta high entropy alloys

This study reports the structure and mechanical properties of new refractory Ti₃₇.₅Nb₁₂.₅Hf₂₅Al₂₅, Ti₄₀Nb₃₀Hf₁₅Al₁₅, and Ti₄₀Nb₂₀Ta₁₀Hf₁₅Al₁₅ (at.%) high entropy alloys. After annealing at 1200 °C for 24 h, the program alloys had a single-phase B2 structure. Further annealing at 600 °C for 24 h resulted in the formation of Widmanstatten orthorhombic particles (O-phase) in the bcc matri

A new refractory Ti-Nb-Hf-Al high entropy alloy strengthened by orthorhombic phase particle

This study reports the structure and mechanical properties of a new refractory Ti₄₀Nb₃₀Hf₁₅Al₁₅ (at.%) high entropy alloy. The alloy was fabricated by vacuum arc melting and had a density of 7.07 ± 0.03 g/cm3. After annealing at 1200 °C for 24 h, the alloy possessed a single-phase B2 structure. Further annealing at 600 °C for 24 h resulted in the formation of Widmanstatten (Ti, Al)-rich orthorhombic particles (O-phase) in a bcc matri

Refractory high entropy alloy with ductile intermetallic B2 matrix / hard bcc particles and exceptional strain hardening capacity

In this study, a new Nb₃₀ Mo₃₀ Hf₂₀ Co₂₀ (at. %) refractory high entropy alloy (RHEA) comprising an intermetallic (Hf, Co)-rich B2 matrix and disordered (Nb, Mo)-rich bcc particles was introduced. The B2 matrix showed relatively high dislocation mobility, which, coupled with its continuity, allowed bridging and blunting of the cracks formed in the hard bcc particles during plastic deformation. The complex deformation behavior of the constitutive phases resulted in extraordinary high strain hardening capacity at 22-600 °C, exceeding single- and multi-phase RHEAs, together with the high strengt

Overcoming the strength-ductility trade-off in refractory medium-entropy alloys via controlled B2 ordering

Controlled Al-induced B2 ordering helps overcome the strength-ductility dilemma in refractory medium-entropy alloys due to solid solution and short-range strengthening coupled with the dislocation motion changin

Unique precipitations in a novel refractory Nb-Mo-Ti-Co high-entropy superalloy

Herein, a novel refractory Nb₃₀Mo₃₀Ti₂₀Co₂₀ (at. %) high-entropy superalloy (RHESA) is introduced. Annealing at 1200 °C led to the precipitation of a semi-coherent individual (Co, Ti)-rich B2, (Ti, O)- rich fcc (Ti-rich oxides), and hierarchical B2+fcc nanoparticles in the (Nb, Mo)-rich RHESA bcc phase. B2+fcc dispersoids were dominant, and they nucleated heterogeneously because of the coherency ensured by the Baker-Nutting orientation relationshi

On the yield stress anomaly in a B2-ordered refractory AlNbTiVZr₀.₂₅ high-entropy alloy

High-entropy intermetallics have a great potential for high-temperature applications. However, there is relatively limited information about the plastic flow behaviour and deformation mechanisms of these materials. Here we reported a yield strength anomaly (YSA) in a refractory AlNbTiVZr₀.₂₅ high-entropy alloy with a multicomponent B2 matrix phas