Effect of plastic deformation on the structure and properties of the Ti/TiB composite produced by spark plasma sintering

A Ti/17 vol % TiB composite material is produced by spark plasma sintering of a mixture of titanium and 10 wt % TiB2 powders at a temperature of 1000°C. Multiaxial isothermal forging is performed at t = 850°C to enhance the mechanical properties of the composit

Evolution of microstructure and mechanical properties of a CoCrFeMnNi High-entropy alloy during high-pressure torsion at room and cryogenic temperatures

High-pressure torsion is applied to a face-centered cubic CoCrFeMnNi high-entropy alloy at 293 and 77 K. Processing by HPT at 293 K produced a nanostructure consisted of (sub)grains of ~50 nm after a rotation for 180°. The microstructure evolution is associated with intensive deformation-induced twinning, and substructure development resulted in a gradual microstructure refinemen

Structure and mechanical properties of B2 ordered refractory AlNbTiVZrx (x=0-1.5) high-entropy alloys

Structure and mechanical properties of the AlNbTiVZrx (x=0; 0.1; 0.25; 0.5; 1; 1.5) refractory high-entropy alloys were investigated after arc melting and annealing at 1200°C for 24 h. The AlNbTiV alloy had a B2 ordered single phase structure. Alloying with Zr resulted in (i) change of the degree of order of the B2 phase; and (ii) precipitation of the Zr5Al3 and C14 Laves ZrAlV phase

Aging behavior of the HfNbTaTiZr high entropy alloy

The HfNbTaTiZr high entropy alloy was produced by vacuum arc melting, homogenized at 1200 C, and annealed at 600-1000 C for 1-100 h. Structure and microhardness of the annealed alloy were investigated. A strong increase of microhardness after aging treatment at 600 C was found. Formation of second hcp phase particles in the bcc matrix after annealing at 600 and 800 C was also revealed. Effect of precipitation of second phase particles on microhardness was analyze

Neutron lifetime measurements using gravitationally trapped ultracold neutrons

Our experiment using gravitationally trapped ultracold neutrons (UCN) to measure the neutron lifetime is reviewed. Ultracold neutrons were trapped in a material bottle covered with perfluoropolyether. The neutron lifetime was deduced from comparison of UCN losses in the traps with different surface-to-volume ratios. The precise value of the neutron lifetime is of fundamental importance to particle physics and cosmology. In this experiment, the UCN storage time is brought closer to the neutron lifetime than in any experiments before:the probability of UCN losses from the trap was only 1% of that for neutron beta decay. The neutron lifetime obtained,878.5+/-0.7stat+/-0.3sys s, is the most accurate experimental measurement to date.Comment: 38 pages, 19 figures,changed conten

Measurement of the neutron lifetime using a gravitational trap and a low-temperature Fomblin coating

We present a new value for the neutron lifetime of 878.5 +- 0.7 stat. +- 0.3 syst. This result differs from the world average value (885.7 +- 0.8 s) by 6.5 standard deviations and by 5.6 standard deviations from the previous most precise result. However, this new value for the neutron lifetime together with a beta-asymmetry in neutron decay, Ao, of -0.1189(7) is in a good agreement with the Standard Model.Comment: 11 pages, 9 figures; extended content with some correction

Structures and mechanical properties of Ti-Nb-Cr-V-Ni-Al refractory high entropy alloys

Four refractory high entropy alloys with different chemical compositions, which can be calculated as Ti(50-1.5625x)Nb(30-0.9375x)Cr₁₀V₁₀Ni₁.₅xAlx (x ¼ 0, 5, 7, 10), were prepared by arc melting to determine the effect of Ni and Al on the phase composition, structure and mechanical properties. Each alloy was studied in both the as-cast and annealed at 1000 °C for 24 h conditions; compression tests at room temperature or at 800 °C was used to examine mechanical behavior of the alloys and the effect of deformation on microstructur