Dispersoid hardening is a key factor in increasing the recrystallization resistance and mechanical strength of non-heat treatable aluminum-based alloys.Mn and Zr are the main elements that form dispersoids in commerci...Dispersoid hardening is a key factor in increasing the recrystallization resistance and mechanical strength of non-heat treatable aluminum-based alloys.Mn and Zr are the main elements that form dispersoids in commercial Al-based alloys.In this work,the annealing-induced precipitation behavior,the grain structure,and the mechanical properties of Al-3.0 Mg-1.1 Mn and Al-3.0 Mg-1.1 Mn-0.25 Zr alloys were studied.The microstructure and the mechanical properties were significantly affected by annealing regimes after casting for both alloys.The research demonstrated a possibility to form high-density distributed quasicrystalline-structured I-phase precipitates with a mean size of 29 nm during low-temperature annealing of as-cast alloys.Fine manganese-bearing precipitates of I-phase increased recrystallization resistance and significantly enhanced the mechanical strength of the alloys studied.The estimated strengthening effect owing to I-phase precipitation was 150 MPa.Due to the formation of L1_(2)-structured Al3Zr dispersoids with a mean size of 5.7 nm,additional alloying with Zr increased yield strength by about 90 MPa.The L1_(2)-phase strengthening effect was estimated through the dislocation bypass looping and shearing mechanisms.展开更多
This work is a study of the effect of co-doping(ZrO_(2))_(0.9)(Sc_(2)O_(3))_(0.1)solid solution with yttria and/or ceria on the phase composition,local structure and transport properties of the crystals.The solid solu...This work is a study of the effect of co-doping(ZrO_(2))_(0.9)(Sc_(2)O_(3))_(0.1)solid solution with yttria and/or ceria on the phase composition,local structure and transport properties of the crystals.The solid solution crystals were grown using directional melt crystallization in cold crucible.We show that ceria co-doping of the crystals does not stabilize the high-temperature cubic phase in the entire crystal bulk,unlike yttria codoping.Ceria co-doping of the(ZrO_(2))_(0.9)(Sc_(2)O_(3))_(0.1)crystals increases their conductivity,whereas the addition of 1 mol.%yttria tangibly reduces the conductivity.Equimolar co-doping of the(ZrO_(2))0.9(-Sc_(2_O_(3))0.1 crystals with ceria and yttria changes the conductivity but slightly.Optical spectroscopy of the local structure of the crystals identified different types of optical centers.We found that the fraction of the trivalent cations having a vacancy in the first coordination sphere in the ceria co-doped crystals is smaller compared with that in the yttria co-doped crystals.展开更多
The development of micromechanical devices(MEMS and NEMS)on the basis of nanostructured shape memory alloys is reported.A Ti_(50)Ni_(25)Cu_(25)(at.%)alloy fabricated by the melt spinning technique in the form of a rib...The development of micromechanical devices(MEMS and NEMS)on the basis of nanostructured shape memory alloys is reported.A Ti_(50)Ni_(25)Cu_(25)(at.%)alloy fabricated by the melt spinning technique in the form of a ribbon with a thickness around 40µm and a width about 1.5 mm was chosen as a starting material.Technological parameters were optimized to produce the alloy in an amorphous state.The thickness of the ribbon was reduced to 5–14µm by means of electrochemical polishing.A nanostructural state of the thin ribbons was obtained via the dynamic crystallization of the amorphous alloy by application of a single electric pulse with duration in the range of 300–900µs.A microtweezers prototype with a composite cantilever of 0.8µm thick and 8µm long was developed and produced on the basis of the obtained nanostructured thin ribbons by means of the focused ion beam technique.Controlled deformation of the micromanipulator was achieved by heating using semiconductor laser radiation in a vacuum chamber of scanning ion-probe microscope.展开更多
基金funded by RFBF grant#20-03-00778the financial support of the Ministry of Education and Science of the Russian Federation in the framework of Increase Competitiveness Program of NUST MISIS for the part of the grain structure analysis。
文摘Dispersoid hardening is a key factor in increasing the recrystallization resistance and mechanical strength of non-heat treatable aluminum-based alloys.Mn and Zr are the main elements that form dispersoids in commercial Al-based alloys.In this work,the annealing-induced precipitation behavior,the grain structure,and the mechanical properties of Al-3.0 Mg-1.1 Mn and Al-3.0 Mg-1.1 Mn-0.25 Zr alloys were studied.The microstructure and the mechanical properties were significantly affected by annealing regimes after casting for both alloys.The research demonstrated a possibility to form high-density distributed quasicrystalline-structured I-phase precipitates with a mean size of 29 nm during low-temperature annealing of as-cast alloys.Fine manganese-bearing precipitates of I-phase increased recrystallization resistance and significantly enhanced the mechanical strength of the alloys studied.The estimated strengthening effect owing to I-phase precipitation was 150 MPa.Due to the formation of L1_(2)-structured Al3Zr dispersoids with a mean size of 5.7 nm,additional alloying with Zr increased yield strength by about 90 MPa.The L1_(2)-phase strengthening effect was estimated through the dislocation bypass looping and shearing mechanisms.
基金Financial support from the Russian Science Foundation(Project 17-79-30071“Scientifically grounded optimization of power and mass-dimensional characteristics of planar SOFC stacksdevelopment of fuel processor for highly-efficient transport and stationary power plants”)is gratefully acknowledged.A part of experimental facilities used for this research were developed in framework of Project 14.B25.31.0018 funded by the Russian Ministry of Education and Science。
文摘This work is a study of the effect of co-doping(ZrO_(2))_(0.9)(Sc_(2)O_(3))_(0.1)solid solution with yttria and/or ceria on the phase composition,local structure and transport properties of the crystals.The solid solution crystals were grown using directional melt crystallization in cold crucible.We show that ceria co-doping of the crystals does not stabilize the high-temperature cubic phase in the entire crystal bulk,unlike yttria codoping.Ceria co-doping of the(ZrO_(2))_(0.9)(Sc_(2)O_(3))_(0.1)crystals increases their conductivity,whereas the addition of 1 mol.%yttria tangibly reduces the conductivity.Equimolar co-doping of the(ZrO_(2))0.9(-Sc_(2_O_(3))0.1 crystals with ceria and yttria changes the conductivity but slightly.Optical spectroscopy of the local structure of the crystals identified different types of optical centers.We found that the fraction of the trivalent cations having a vacancy in the first coordination sphere in the ceria co-doped crystals is smaller compared with that in the yttria co-doped crystals.
基金This work has been carried out in the frames of Federal Target Program of Russian Federation,GK No.P726 and No.14.740.11.0687.
文摘The development of micromechanical devices(MEMS and NEMS)on the basis of nanostructured shape memory alloys is reported.A Ti_(50)Ni_(25)Cu_(25)(at.%)alloy fabricated by the melt spinning technique in the form of a ribbon with a thickness around 40µm and a width about 1.5 mm was chosen as a starting material.Technological parameters were optimized to produce the alloy in an amorphous state.The thickness of the ribbon was reduced to 5–14µm by means of electrochemical polishing.A nanostructural state of the thin ribbons was obtained via the dynamic crystallization of the amorphous alloy by application of a single electric pulse with duration in the range of 300–900µs.A microtweezers prototype with a composite cantilever of 0.8µm thick and 8µm long was developed and produced on the basis of the obtained nanostructured thin ribbons by means of the focused ion beam technique.Controlled deformation of the micromanipulator was achieved by heating using semiconductor laser radiation in a vacuum chamber of scanning ion-probe microscope.
