6 Works

Burst-like shape memory recovery and calorimetric effect in Cu-Al-Ni alloy single crystals at cyclic test

L.I. Guzilova, V.I. Nikolaev, P.N. Yakushev, S.I. Stepanov, R.B. Timashov, A.V. Chikiryaka & S.A. Pulnev
Here we report on compressive stress-strain behavior, ordinary and burst-like shape memory (SM) strain recovery, and associated caloric effects in Cu – 14.02% wt. Al – 4.0% wt. Ni single crystals which have multiphase martensitic structure at room temperature. The effect of repetitive thermo-mechanical cycling on the recovery of the shape memory deformation is investigated. The stress-strain curves of the specimens are smooth in all tests. Immediately after quenching, crystals exhibited burst-like strain recovery accompanied...

WEAR RESISTANCE OF α- AND β- GALLIUM OXIDE COATINGS

P.N. Butenko, L.I. Guzilova, A.V. Chikiryaka, A.I. Pechnikov, A.S. Grashchenko, A.O. Pozdnyakov & V.I. Nikolaev
Mechanical wear resistance of the α- and β- Ga2O3 polymorphs is experimentally studied. We report about tribological cyclic tests of these wide-band-gap semiconductor crystals. To the best of our knowledge, this is the first attempt at considering these crystals as protective coatings. The crystalline layers were deposited on sapphire substrates by vapour-phase epitaxy. This method allows applying coatings on large areas and surfaces of complex shapes, including the surfaces of a number of metals. It...

ALGORITHM FOR POSITIONING OF ROTARY ACTUATORS BASED ON SHAPE MEMORY Cu-Al-Ni TENSILE FORCE ELEMENTS

A. Priadko, S. Pulnev, O. Kovalev & I. Ilin
This paper considers positioning algorithms for rotary actuators based on shape memory Cu-Al-Ni crystals. The actuator function scheme is provided. An algorithm for positioning of the actuator based on an actual rotary angle has been developed. Experimental results on the control algorithm and the actuator are presented. The functional characteristics of the actuator (rotation speed and positioning accuracy) are considered.

HVPE growth of corundum-structured α-Ga2O3 on sapphire substrates with α-Cr2O3 buffer layer

S.I. Stepanov, V.I. Nikolaev, A.V. Almaev, A.I. Pechnikov, M.P. Scheglov, A.V. Chikiryaka, B.O. Kushnarev & A.Y. Polyakov
Gallium oxide films were grown by HVPE on (0001) sapphire substrates with and without α-Cr2O3 buffer produced by RF magnetron sputtering. Deposition on bare sapphire substrates resulted in a mixture of α-Ga2O3 and ε-Ga2O3 phases with a dislocation density of about 2∙1010 cm-2. The insertion of α-Cr2O3 buffer layers resulted in phase-pure α-Ga2O3 films and a fourfold reduction of the dislocation density to 5∙109 cm-2.

ANALYTICAL DESCRIPTION OF QUANTUM EFFECTS AT CURRENT FILAMENTATION IN CHALCOGENIDE GLASSES

N. Sovtus & K. Mynbaev
Quantum effects occurring during current filamentation in a chalcogenide glass are considered. Under the conditions considered, the current filament appears as a set of concentric tubes with different temperatures. In every tube, the electron has a specific wave function and a specific energy level. The radii of the tubes appear to be proportional to natural numbers n. The dependence of maximal temperature on the electrical field is obtained. The Schroedinger equation is reduced to the...

JUMPING AT STRAIN RECOVERY IN SHAPE MEMORY Cu-Al-Ni SINGLE CRYSTALS

V.I. Nikolaev, R.B. Timashov, S.A. Pulnev, L.I. Guzilova, P.N. Butenko & S.I. Stepanov
Shape memory Cu-Al-Ni single crystals of two alloy compositions Cu 82.5 wt.% - Al 13.5 wt.% - Ni 4.0 wt.% and Cu 81.98 wt.% - Al 14.02 wt.% - Ni 4.0 wt.% have been studied in view of their ability to undergo spontaneous jumping during reverse martensitic transformation. Crystals of both alloys were compressively deformed up to a full shape memory strain (8%) at room temperature. It was found that specimens of the first alloy...

Registration Year

  • 2021
    6

Resource Types

  • Text
    6

Affiliations

  • Ioffe Institute
    6
  • Tomsk Polytechnic University
    1
  • National University of Science and Technology
    1
  • Peter the Great St. Petersburg Polytechnic University
    1
  • Institute of Problems of Mechanical Engineering
    1