High-molecular-weight metathesis polynorbornene containing triethylene glycol fragments linked to the main chain through a carboxyl group has been synthesized for the first time. Gas-transport parameters of the polynorbornene were investigated for the extended set of gases: H2, He, Ar, N2, O2, CO2, CH4, C2H2, C2H4, C2H6, C3H6, C3H8, CHF3, CH2F2, CF2Cl2, CHF2Cl, and NH3. The gas-transport properties of the polymer are stable during six months. The increased permeability coefficients of CO2, ethylene, acetylene, propylene, freons and ammonia are determined by their high solubility coefficients. The point for the polymer synthesized in the work is located higher than the 2008 Robeson upper bound in the selectivity-permeability diagram for CO2/N2 gas pair, which arises from the specific interaction of CO2 with the polymer. The analysis of specific interactions was carried out using correlation ratios of diffusion coefficients with the effective cross-section of gas molecules and solubility coefficients with Abraham parameters. Nonspecific and specific solubility and diffusion coefficients and their ratios for CO2, acetylene, ethylene, propylene, freons and ammonia were obtained. Based on the data obtained, the Abraham coefficients for the synthesized polymer (the "fingerprint" of the polymer) are calculated, which make it possible to estimate the solubility coefficient of gas or vapor for which the Abraham parameters are tabulated. The diffusion coefficients of gas or vapor for which the values of the effective cross-section of the molecule are tabulated can be estimated using the Teplyakov-Meares model, and, consequently, the permeability coefficient can be calculated. The proposed model has significant potential, however, given that the values obtained are calculated, the predicted gas transport parameters of the polymer are estimates.

An Al-Mg-Ca-Sc alloy with low hot cracking susceptibility was designed and fabricated by laser powder bed fusion technology. A hierarchical microstructure, i.e., solute Mg, dispersed nanoscale Al3(Sc, Zr) precipitates in the grains and a discontinuous network of Al4Ca phases along grain boundaries, was constructed. The mechanical properties of the additively manufactured (AMed) alloy showed superior strength and ductility. The strengthelongation product of the AMed alloy is over eight times higher than that of the cast alloy at both room and elevated temperatures. The alloy retains 66% of its ultimate strength due to the high thermal stability of the microstructure whereas only 31% was left for the AMed Scalmalloy, when the temperature increased from room temperature to 200 degrees C. Ab initio calculations revealed a strong grain boundary segregation tendency for Ca, whereas the segregation tendency was weak for other elements, unraveling the origin of the hierarchical microstructure.

Abstract—The thermal stability of the Al–4 wt

The paper presents the design features and technology of the formation of a low-pressure sensor, which is a heater deposited onto the surface of a porous aluminum-oxide membrane formed on aluminum foil. The structure is fully formed using inexpensive low temperature methods. It is shown that an increase in the porosity of the membrane region separating the heating element and the substrate makes it possible to effectively measure a pressure up to 2 × 10–2 Pa.

В данном исследовании на примере холоднокатаных листов было изучено раздельное влияние магния и цинка в количестве до 2% на структуру и механические свойства термически не упрочняемого термостойкого сплава Al–2%Cu–1,5%Mn, состав которого оптимизирован для получения максимальной доли фазы Al20Cu2Mn3. Установлено, что в литом состоянии цинк полностью находится в составе алюминиевого твердого раствора, магний частично входит в эвтектические частицы фазы Al2CuMg. Эти элементы практически не влияют на количество фазы Al20Cu2Mn3, которая формируется в процессе деформационно-термической обработки в виде наноразмерных дисперсоидов. Установлено, что добавление 1% магния повышает прочность холоднокатаных листов базового сплава на 15% после 3-ч отжига при 400 °С без снижения пластичности. Легирование цинком в свою очередь не оказывает существенного влияния на прочность. In this study, using the example of cold-rolled sheets, the separate effect of magnesium and zinc in an amount of up to 2% on the structure and mechanical properties of a thermally non-hardening heat-resistant alloy Al–2%Cu–1.5%Mn, the composition of which is optimized to obtain the maximum fraction of the Al20Cu2Mn3 phase, was studied. It was found that in the cast state, zinc is completely contained in the aluminum solid solution, magnesium is partially included in the eutectic particles of the Al2CuMg phase. These elements practically do not affect the amount of the Al20Cu2Mn3 phase, which is formed during deformation and heat treatment in the form of nanoscale dispersoids. It was found that the addition of 1% magnesium increases the strength of cold-rolled sheets of the base alloy by 15% after 3-hour annealing at 400 °C, without reducing the plasticity. Zinc alloying, in turn, does not have a significant effect on strength.

A set of new norbornene-type monomers containing linear and branched substituents with three C-O-C fragments was synthesized in good yields from commercially available glycerol and diethylene glycol monomethyl ether. Vinyl-addition polymerization of the synthesized monomers was systematically studied, and highly active Pd-catalysts that made it possible to reach quantitative conversions of the monomers were suggested for their polymerization. As a result, robust thin membranes were successfully prepared directly from the polymerization mixtures in the air. Gas separation performance for a wide range of gases was evaluated for the synthesized polymers, and new valuable structure-property relationships were found. More specifically, these membranes display the facilitated transport of CO2 and solubility-controlled hydrocarbon separation selectivity. The increase in the amount of C-O-C fragments in side chains enhances these effects, but only in the case of the linear structure of the substituents. If the structure of side chains becomes branched, the gas permeability is reduced, the facilitated transport of CO2 is minimized, and the polymer becomes more susceptible to plasticization by butane. The facilitated transport of CO2 is due to the specific dipole-quadrupole interaction between CO2 molecules and polymer matrix. For the studied polymers, the contribution of this specific interaction to the solubility of CO2 achieves 64 %. The significant influence of alkyl tails in side chains on gas transport properties was also observed. To achieve better gas separation performance, it is desirable to incorporate short and rigid alkyl tails. Thus, among substituents containing ether moieties, linear oligoethylene glycols with methyl tails seem to be the most promising side-chain substituents for the macromolecular design of CO2-selective polymeric membrane materials. The results obtained were considered along with NMR, TGA, DSC, DMA, and WAXD data.

In this work, films of polyvinylidene fluoride, copolymer of vinylidene fluoride and trifluoroethylene have been studied. The samples were made by direct ink writing technology. Some of the produced films were polarized in the corona discharge field. The dependences of the relative permittivity on temperature were studied for the films. The study showed that for polyvinylidene fluoride films, no maximum is observed in the dependences of the permittivity on temperature, since the assumed temperature of the ferroelectric phase transition is higher than the melting temperature. The maximum in the temperature dependence of permittivity for polarized copolymer of vinylidene fluoride and trifluoroethylene films is shifted by 10 degrees C toward higher temperatures compared to the maximum for non-polarized films. In this case, the permittivity of non-polarized films has higher values compared to the corresponding value for polarized samples. This is due to an increase in the proportion of the beta-phase after polarization, as well as to the internal electric field caused by the space charge formed during the polarization process at the phase boundaries.

The aluminum corner of the previously unexplored quaternary eutectic Al-Cu-Ca-Si system promising for the design of new heat treatable alloys have been studied using thermodynamic modeling and experimental techniques. The experimental data have revealed the presence in equilibrium of a previously undescribed quaternary compound identified as a strict stoichiometric Al2CaSiCu phase with a tetragonal I4/mmm structure (Pearson symbol: tI10) and the lattice parameters a = 4.04Å and c = 11.00Å. The phase has a density of 3.36g/cm3 and a microhardness of 335 Hv. In accordance with the suggested structure of the phase diagram, its region that can be promising for the design of heat treatable alloys contains three (Al)+Al2Cu+Al2CaSiCu, (Al)+Al2Si2Ca+Al2CaSiCu and (Al)+Al2Cu+Al2Si2Ca quasi-ternary sections and two (Al)+Al2Cu+Al2Si2Ca+Al2CaSiCu and (Al)+Al2Cu+Al2CaSiCu+Si four-phase fields. Analysis of the precipitation hardening response for the new quaternary Al-5wt.%Cu-Ca-Si alloys suggests that it is not inferior (the obtained peak hardness is ~125 Hv) to that for the alloys Al-5wt.% Cu (~120 Hv) and Al-4wt.%Si-5wt.%Cu (~125 Hv) based on the conventionally used systems. However, to obtain noticeable hardening at aging, the content of silicon should be at least 1.1-1.2 times higher than that of calcium. A comparative hot tearing susceptibility (HTS) study revealed that the new heat treatable Al-5wt.%Cu-Ca-Si alloys have higher hot tearing resistances (HTS ~16mm according to a pencil probe) than that of the Al-5wt.%Cu base alloy (HTS >16mm).

In this work, a thermally stable model Al-4Cu-3Mn (wt%) alloy has been manufactured by electromagnetic casting (EMC), followed by compression, intermediate heat treatment and high-pressure torsion (HPT). Structural changes of the alloy during subsequent processing stages have been analysed by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and the X-ray diffraction (XRD). The results indicate that variations in the intermediate heat treatment temperature of the compressed samples lead to a significant difference in strain hardening and thermal stability after HPT. According to microstructure investigations the hardening of samples processed by HPT resulted from formation of mixture of grains and subgrains with high dislocation density as well as mechanical fragmentation of eutectic Al2Cu particles and precipitation of nanoscale Mn-rich dispersoids which are identified as Al6Mn. The intermediate heat treatment of the EMC rod at 350 degrees C for 3 hours and heat treatment of HPT sample at 250 degrees C for 5 hours exhibited the best mechanical properties in terms of ultimate tensile strength (UTS), yield strength (YS) and elongation (El), reaching 610 MPa, 560 MPa and 10% respectively. At the same time intermediate annealing at 450 degrees C makes the HPT processing ineffective.

The Al-Cu-Mn-Ca system was proposed as a bases for the design of new group of heat-resistant alloys which can be used for high-temperature applications instead of the 2219 types industrial alloys. Unlike the latter ones, the new alloys also do not require a full cycle of strengthening heat treatment including solid solution treatment, quenching and aging. The effect of calcium addition in the 1-4 wt% range on the structure, phase composition and hardness after high temperature annealing of the Al-6 %Cu-2 %Mn base sheet alloy has been studied. It has been shown that calcium addition leads to the formation of high-temperature eutectics (614-617 degrees & Scy;) with the participation of the Al27Ca3Cu7 and (Al,Cu)4Ca phases that are capable of spheroidization at high temperature annealing. The ingots of Ca-containing alloys do not require homogenization but have sufficient deformation plasticity at both hot and cold rolling. The structure of the previously unstudied quaternary Al-Cu-Mn-Ca phase diagram in the region of the aluminum corner has been also proposed, according to which it can contain 5 fourphase fields in the solid state with the participation of (Al), binary (Al2Cu, Al4Ca, Al6Mn) and ternary (Al8CaCu4, Al27Ca3Cu7, Al10CaMn2 and Al20Cu2Mn3) phases. Based on the obtained data, the composition Al-6 %Cu-2 % Mn-1 %Ca has been proposed as a basis for the development of a new heat-resistant alloy. It is shown that this alloy superior to industrial 2219 alloy in terms of heat resistance, especially after annealing at 400 degrees C, when the difference in hardness reaches 32 HV. The high heat resistance of the new wrought alloy originates from the formation of a specific microstructure consisting of fine Ca-containing eutectic inclusions and Al20Cu2Mn3 phase dispersoids with a size of about 100 nm which prevent recrystallization and allow maintaining the fine subgrained structure.

The structure and properties of the new (Al,Cu)4Ca, Al27Ca3Cu7, and Al8CaCu4 intermetallic compounds in equilibrium with aluminum solid solution in the ternary Al–Ca–Cu alloying system were comprehensively analyzed. The (Al,Cu)4Ca intermetallic compound is treated as a line phase based on the Al4Ca phase with Cu substituted by Al. The solubility of copper in the compound reaches 10 at.% (19 wt.%), which leads to marked changes in the crystal lattice structure, physical and mechanical properties of the compound. For instance, the density of the compound increases from 2.22 to 2.79 g/cm3 and the microhardness from HV 180 to HV 250. The Al27Ca3Cu7 phase is treated as a strict stoichiometric ternary compound with a primitive BaHg11 type crystal structure of the Pm3m space group. The lattice parameter is accepted to be 8.514 Å corresponding to a density of 3.45 g/cm3. The Al8CaCu4 phase is also a strict stoichiometric ternary compound with a tetragonal crystal lattice structure of the Mn12Th type. The phase has the highest microhardness (HV 505) and density (4.57 g/cm3). The alloys pertaining to the binary (Al)+(Al,Cu)4Ca phase field and the quasi-binary (Al)+Al27Ca3Cu7 section can be considered promising as the base for new natural aluminum matrix composites.

The phase diagram of the Al−Ca−Fe system in the aluminum corner, including the liquidus projection and solidification reactions, was studied by using thermodynamic calculations and experimental techniques. The results show that instead of the Al3Fe phase, a ternary compound whose composition corresponds to the formula Al10CaFe2 should be in equilibrium with the aluminum solid solution (Al). Thе transition from the binary to the ternary compound occurs via the peritectic transformation L + Al3Fe → (Al) + Al10CaFe2 (at 638 °C, 3.3 at.% Ca and 0.5 at.% Fe). Primary and eutectic crystals of the ternary compound have a compact morphology, in contrast to needle-shaped inclusions of the Al3Fe phase. First principles calculations and X-ray diffraction analysis were used to determine the crystal lattice structure of Al10CaFe2 ternary compound. In addition, the near eutectic alloy Al−6wt.%Ca−1wt.%Fe after annealing at 500−600 °C has a fine structure with a total fraction of excess phases of about 25 vol.%. Thus, the Al−Ca−Fe system can be used to create new aluminum-matrix composite alloys.

Based upon the Al-Cu-Mn system, aluminum hypoeutectic heat resistant aluminum alloy of the Al4Cu2Mn0.5Ca0.2Zr (wt.

Using computational and experimental methods, the influence of deformation-heat treatment on the structure, electrical resistance and hardness of the Al–4 %Cu–3 %Mn alloy produced by casting in an electromagnetic crystallizer was studied. It has been shown that at a cooling rate of more than 1000 K/s, the entire amount of manganese and half of the total copper content are dissolved in the aluminum solid solution, which allows, with subsequent deformation-thermal treatment, to form a structure with the maximum possible number of Al20Cu2Mn3 dispersoids, which allows achieving significant increasing heat resistance compared to known alloys of the Al–Cu–Mn system.

The phase composition of the Al–Cu–Ca–Mn alloys containing (wt

На основе системы Al–Cu–Mn разработан, получен и исследован алюминиевый доэвтектический сплав с повышенной термической стойкостью состава Al4Cu2Mn0,5Ca0,2Zr (масс. %) (П2). Эффект увеличения термостойкости достигнут благодаря наноразмерным дисперсоидам интерметаллидов Al20Cu2Mn3 и Al3Zr, а также путем дополнительного легирования добавкой эвтектикообразующего элемента, роль которого играет кальций. Установлено, что резервы легирования алюминиевой матрицы в поршневых силуминах практически исчерпаны пределом растворимостей кремния, меди и магния в алюминиевом твердом растворе. Для обоснования химического состава поршневого силумина П1 проведен расчет фазового состава системы Al–Si–Cu–Mg–Ni–Fe–Mn с помощью программного обеспечения Thermo-Calc. Исследована микроструктура сравниваемых сплавов с помощью методов электронной микроскопии (СЭМ) и микрорентгеноспектрального анализа (МРСА). Проведено сравнение твердости по Виккерсу предложенного сплава П2 и эвтектического поршневого силумина П1, в исходном состоянии и после отжига при температурах от 250 до 400 °С, с шагом в 50 °С, в результате чего, разработанный сплав П2 более эффективно сохраняет свою твердость при нагреве, нежели сплав П1, потенциально являясь более термостойким. Based on the Al–Cu–Mn system, aluminum hypoeutectic heat resistant aluminum alloy Al4Cu2Mn0,5Ca0,2Zr (wt. %) (P2) was developed, synthesized and investigated. Effect of high heat resistance was obtained because of nanoscaled intermetallic dispersoids of Al20Cu2Mn3 и Al3Zr with the effect of induced eutectic formation due to calcium addition. It is determined, that in the Al–Si piston alloys, because of the solubility limit of silicon, coper and magnesium in the aluminum solid solution, there is not much to alloying aluminum matrix with. Phase composition of eutectic Al-Si alloy named AK12M2MgH (P1) was calculated with Thermo-Calc software to justify its chemical composition. Microstructure of the compared alloys was investigated with the scanning electron microscopy (SEM) and electron probe microanalysis (EPMA) methods. Vickers hardness of P1 and P2 alloys hot rolled sheets was studied for as-synthesized sheets and after thermal treatment at 250-400 °C (for each 50 °C). After comparing results of hardness, it was concluded, that developed heat resistant hypoeutectic aluminum alloy retain hardness more effectively than eutectic piston alloy P1.

Based upon the Al-Cu-Mn system, aluminum hypoeutectic heat resistant aluminum alloy of the Al4Cu2Mn0.5Ca0.2Zr (wt. %) (P2) composition is developed, synthesized, and studied. An effect of increasing thermal stability is achieved due to nanosize dispersed intermetallics Al20Cu2Mn3 and Al3Zr, and also with addition of eutectic-forming elements, whose role is played by calcium. It is established that reserves of alloying an aluminum matrix within piston silumin is almost exhausted by the limit of silicon, copper and manganese solubility within aluminum solid solution. In order to substantiate the piston silumin P1 chemical composition a calculation is made for the phase composition of the Al-Si-Cu-Mg-Ni-Fe-Mn system by means of Thrmoclac software. Welded alloy microstructure is studied by means of electron microscopy (SEM) and X-ray microanalysis (XRMA). Vickers hardness of the alloy proposed P2 and equivalent piston silumin P1 is compared in the original condition and after annealing at 250 and 400 degrees C with a step of 50 degrees C, as a result of which alloy P2 developed retains more effectively hardness on heating, than for alloy P1, being potentially more heat resistant.