I. G. Korol’kova

Phase equilibria in solid Mg-Rich Mg-Sm-Tb alloys

The structure of Mg-rich Mg-Sm-Tb alloys with samarium and terbium contents up to 30 at % each is studied by metallography, electron microprobe analysis, and electrical resistivity measurements. The magnesium-based solid solution is found to be in equilibrium only with the Mg41Sm5 and Mg24Tb5 phases belonging to the Mg-Sm and Mg-Tb binary systems composing the ternary system, respectively. The individual and total samarium and terbium solubilities in a magnesium-based solid solution at 500 and 300°C are determined. The terbium and samarium solubilities in the Mg41Sm5 and Mg24Tb5 phases, respectively, are also determined. Partial isothermal sections at 500 and 300°C of the Mg-Sm-Tb phase diagram in the Mg- rich region are constructed.

Phase equilibria in the ternary Al-Sc-Mn system

Optical microscopy, electron microprobe analysis, and electrical resistivity measurements are used to study Al-Sc-Mn alloys containing up to 3 at % Sc and to 2.5 at % Mn. The boundaries of the Al-based solid solution are determined at 640, 600, and 400°C, and the isothermal section of the Al-rich portion of the Al-Sc-Mn system at 640°C is constructed. The Al-based solid solution is found to be in equilibrium with the ScAl3 and MnAl6 phases.

Study of the phase equilibria and the decomposition of a supersaturated solid solution in magnesium alloys with aluminum, calcium, and manganese

Magnesium alloys Mg-Al-Ca-Mn having 1 wt % Al, up to 1.8 wt % Mn, and up to 1.6 wt % Ca are studied by optical microscopy, electron microprobe analysis, and electrical resistivity and microhardness measurements. The phase equilibria corresponding to the Al, Ca, and Mn concentration ranges under study were determined and sections of the isothermal tetrahedrons of the Mg-Al-Ca-Mn phase diagram in the Mn-rich region at 450 and 300°C have been constructed. As was found, manganese does not affect the decomposition kinetics of the magnesium supersaturated solid solution in ternary Mg-Al-Ca alloys but increases their hardness.

Phase compositions of Al-rich Al-Cr-Sc alloys at 640 and 600°C

Al-Cr-Sc alloys annealed at 640 and 600°C have been studied by electrical resistivity and hardness measurements, metallography, X-ray diffraction, and electron microprobe analysis. Only the Al3Sc and Al7Cr phases, which belong to the associated binary systems, are found to be in equilibrium with the (Al) solid solution. Isotherms of the chromium and scandium solubility in solid aluminum and an isothermal section of the Al-Cr-Sc system at scandium concentrations up to 1.2 wt % and chromium concentrations up to 1.0 wt % are plotted.

Section of the isothermal tetrahedron of the Al-Cu-Mg-Zr phase diagram at 490°C

The phase equilibria in the Al-Cu-Mg-Zr system at 490°C have been studied for Al-rich alloys with 0.3% Zr and from 0 to 10% Cu or Mg. The (Al) solid solution is found to be in equilibrium with only binary θ(CuAl2) and ZrAl3 and ternary S (CuMgAl2) phases of the ternary Al-Cu-Mg system. The section of the isothermal tetrahedron of the Al-Cu-Mg-Zr phase diagram at 490°C, which corresponds to 0.3% Zr and up to 10% Cu or Mg, is constructed.

Phase composition of Al-Rich Al-Sc-Cr-Zr alloys at 640, 600, and 500°C

Metallographic and electron microprobe analyses and hardness and electrical resistivity measurements are used to study Al-rich Al-Sc-Cr-Zr alloys annealed and quenched from 640, 600, and 500°C. The boundaries of Al-based solid solution are determined; the Al-based solid solution is found to be in equilibrium with the CrAl7 compound and ScAl3- and ZrAl3-based phases, in which zirconium and scandium are dissolved, respectively. Sections of isothermal tetrahedra at 640, 600, and 500°C are constructed.

Liquidus surface of the Mg-Sm-Tb phase diagram

Differential thermal, electron microprobe, and X-ray diffraction analyses and metallography are used to study Mg-Sm-Tb alloys containing up to 30% Sm or Tb. Polythermal sections and the solidification surface of the Mg-Sm-Tb phase diagram are constructed for the Mg-rich region. In the composition range under study, nonvariant transition-type equilibrium L + Mg24Tb5 = (Mg) + Mg41Sm5 is found to exist at a temperature of 539°C.

Effect of Samarium on the Properties of Mg–Y–Gd–Zr Alloys

The microstructure, the aging kinetics, and the strength properties of Mg–Y–Gd–Zr cast alloys, in particular, a samarium-alloyed IMV7-1 alloy, at room and high (250, 300°C) temperatures after homogenization without and with subsequent aging are studied. Alloying with samarium accelerates the decomposition of the supersaturated magnesium solid solution and enhances the properties of the Mg–Y–Gd–Zr alloys.

Effect of dysprosium on the kinetics and structural transformations during the decomposition of the supersaturated solid solution in magnesium–samarium alloys

The effect of dysprosium added in the amounts such that it does not form an individual phase in equilibrium with solid magnesium on the decomposition of the supersaturated magnesium solid solution in Mg–Sm alloys is studied. The presence of dysprosium in Mg–Sm alloys is found to retard the decomposition of the supersaturated magnesium solid solution and to increase the hardening effect upon aging. When these alloys are aged, dysprosium is partly retained in the magnesium solid solution and partly enters into the compositions of the phases that form during the decomposition of the solid solution and are characteristic of Mg–Sm alloys.

Effect of Plastic Deformation on the Structure and Properties of Alloy IMV7-1 of the Mg – Y – Gd – Zr System

The microstructure and strength properties of hot-pressed alloy IMV7-1 of the Mg – Y – Gd – Zr system are studied after additional cold and hot rolling deformation. It is shown that the strength properties of the pressed alloy can be elevated by cold deformation at an admissible level of ductility.