The intermetallic compound Al2Pt has potential of use in radiation sensing devices and selective solar absorbers, and is a promising protective coating of jet engine turbine blades. In our study, we demonstrate for the first time the possibility of forming nanocrystallites of the Al2Pt intermetallic compound in an Al-Pt disc produced by high pressure torsion (HPT) of elemental chips at cryogenic temperature. The composition of the Al + Pt mixture corresponds to the Al2Pt stoichiometry. Microhardness dependences against the distance from the disc center have been plotted and phase composition in the different points has been investigated. The formation of some high-strength phases was confirmed by a significant increase in microhardness near the edge of the cryodeformed Al-Pt disc. The Al2Pt intermetallic phase and amorphous phase were revealed both in XRD-scans and TEM-observations. The spread of Al2Pt crystallites sizes is wide and ranges from 10 to 200 nm. It was found that the amorphous phase had a composition of about 85Al-15Pt (at

The production of Al-based composites with high functional properties is an urgent scientific problem, the results of which may be of interest for practical application. That is why, there is an increasing interest in using the high pressure torsion (HPT) method to consolidate mixtures of aluminum with different metal powders and obtain new materials with promising properties. In the work, we obtained a novel metal-matrix composite, in which a soft Al-matrix is strengthened by hard and inert Pt-particles. The evolution of the phase composition and microhardness of the discs, which were produced by HPT of mixture Al+Pt chips, are investigated. Severe plastic deformation and large shear strain implemented under HPT lead to amorphization and solid solutions based on both Al and Pt. According to our estimation, near 5 at.% Al dissolved in Pt after the room-temperature HPT. Despite the fact that Pt is practically insoluble in Al, the XRD results of the Al-Pt disc suggest the formation of a non-equilibrium solid solution containing 2.1 at.% Pt in the Al matrix. The aluminum and platinum disks were also obtained and investigated. It was revealed, that the microhardness of the Al-Pt composite disc is between the microhardness values of Al- and Pt-discs.

The microstructural evolution of the ordered Cu–56 at % Au alloy under plastic deformation has been studied. It has been revealed that under the influence of deformation, the с -domain structure is originally destroyed, and the lamellar structure demonstrates a higher stability under deformation impacts. It has been demonstrated that deformation to 70% leads to the formation of ultrafine-grained two-phase (order + disorder) structure in the alloy. Based on the results of mechanical tensile tests, the deformation behavior of the ordered and disordered alloys has been analyzed. It has been concluded that the mechanical properties of the moderately deformed (to ~20%) ordered Cu–56 at % Au alloy may be of interest for practical applications.

The microstructural evolution of the ordered Cu–56 at % Au alloy under plastic deformation has been studied. It has been revealed that under the influence of deformation, the с-domain structure is origi-nally destroyed, and the lamellar structure demonstrates a higher stability under deformation impacts. It has been demonstrated that deformation to 70% leads to the formation of ultrafine-grained two-phase (order + disorder) structure in the alloy. Based on the results of mechanical tensile tests, the deformation behavior of the ordered and disordered alloys has been analyzed. It has been concluded that the mechanical properties of the moderately deformed (to ~20%) ordered Cu–56 at % Au alloy may be of interest for practical appli-cations.

Министерство науки и высшего образования Российской Федерации Российская академия наук Научный совет по неорганической химии РАН Научный совет по аналитической химии РАН Научный совет по химической технологии РАН Российское химическое общество имени Д.И

A mixture of fine powder of the Al2Au intermetallic compound and coarse Cu-powder was processed by the ball milling (BM) technique. The phase composition of the obtained powder product and the microstructure of separate particles were studied by TEM, SEM and XRD methods. It was found that BM for 4 h leads to the formation of Cu-clusters that are evenly distributed among the Al2Au-particles. There was discovered a decrease in the lattice parameter of the Al2Au-phase, which is associated with the formation of a solid solution of copper in Al2Au. The crystallite size in the resulting powder is near 20 nm. The mechanical properties of the (Al2Au + Cu)-powder were evaluated using nanoindentation tests. (c) 2021 Elsevier B.V. All rights reserved.

The evolution of the structure, electrical resistivity and microhardness of the non-stoichiometric Cu-56Au (at%) alloy during the disorder <-> order phase transitions of samples with different thermo-mechanical histories has been studied. It was found that the rate of atomic ordering of the Cu-56Au alloy was much lower compared to the equiatomic Cu-50Au alloy that had been well studied earlier. It was shown that the deformation of the quenched alloy slowed down the rate of atomic ordering. It was established that annealing of the quenched alloy for 1 week at 250 degrees C led to the formation of the CuAuI phase with a degree of long-range atomic order S approximate to 0.8. The electrical resistivity of the alloy in this state is rho = (7.75 +/- 0.04) x 10 = (7.75 +/- 0.04) x 10(-8) Omega m, which is the lowest value known for this alloy. It was revealed that the ordered CuAuII phase forms as a result of annealing of the Cu-56Au alloy at high temperature followed by slow cooling to room temperature. During the experiments, we did not receive any data confirming the CuAuII -> CuAuI transition both at heating and at cooling of the alloy. There was made a conclusion of a high thermal stability of the ordered orthorhombic CuAuII phase in the alloy under investigation. (C) 2021 Elsevier B.V. All rights reserved.