Yu. I. Buyanov

Phase diagram of the system titanium-copper

SummaryThe methods of metallographic, thermographic, x-ray diffraction, and microhardness analyses were used for studying alloys of the system titanium-copper in the concentration range 20–100 at. % Cu. On the basis of the results obtained and literature data, the phase diagram of the system Ti-Cu was plotted.It is shown that the system has six intermetallic compounds, of which Ti2Cu, TiCu, and TiCu4 are variable-composition phases with narrow regions of homogeneity.The existing data on the crystalline structures of the phases based on Ti2Cu, TiCu, Ti3Cu4 and TiCu2 have been confirmed and the space group of the phase based on Ti2Cu3 has been determined. It is shown that the intermediate phase with the highest copper content has the formula TiCu4 and a crystalline lattice with a rhombic cell containing 20 atoms.The compounds Ti2Cu and TiCu melt congruently at 1015 and 984° C, respectively, while the compounds Ti3Cu4, TiCu2, and TiCu4 form from the melt by peritectic reactions at 918, 878, and 870° C, respectively. TiCu2 exists only at high temperatures and decomposes at 850° C into TiCu4 and Ti2Cu3. The compound Ti2Cu3 exists below 865° C and forms either at that temperature by the reaction TiCu2 + Ti3Cu4 → 2Ti2Cu3 or at 850° C as a result of the decomposition of the compound TiCu2.The coordinates of the three eutectics in this system are: Theβ-Ti + Ti2u eutectic occurs at 1003° C and 31 at. % Cu, the Ti2Cu+TiCu eutectic at 960° C and 43 at. %Ce, and the TiCu2 + TiCu4 eutectic at 860° C and 73 at. % Cu.

Constitution diagram of the system titanium-silver

SummaryThe titanium-silver phase diagram was investigated over the concentration range from 20 to 100 at. % Ag by means of metallographic, thermal, and x-ray diffraction analyses. It was confirmed that the system contains two intermediate phases,η andγ. The phases are based on the compounds TiAg andTi2Ag, which are isostructural with the compounds TiCu and Ti2Cu. The temperatures of nonvariant transformations were determined, and the character of the transformation taking place in the silver-rich alloys was established.

Phase equilibria in the erbium-silicon system

The structure and phase composition have been examined by microstructure, x-ray phase, and differential thermal analysis for cast and annealed erbium–silicon alloys. The complete phase diagram for the erbium–silicon system has been compiled for the first time.

The liquidus surface of the system titanium-copper-silver

ConclusionsThe liquidus surface of the system titanium-copper-silver was studied by metallographic and thermal analysis methods. Projections were constructed of liquidus surface isotherms on the plane of the concentration triangle, and the shape of the simultaneous-crystallization curves of various phases (boundary curves) was determined.

Phase composition and thermodynamic properties of alloys of the Te—PbTe—Sb2Te3 system

The phase composition and thermodynamic properties of Te−PbTe−Sb2Te3 alloys are determined by means of X-ray phase analysis and measurements of electromotive forces in the temperature range 540–660 K. The formation of the Pb2Sb6Te11 ternary compound in this temperature range has not been confirmed. The results of the electrochemical measurements confirm the mutual solubility of the components of the quasibinary PbTe−Sb2Te3 system. The activities of PbTe are determined in the (PbTe+Sb2Te3) phase field.

Thermodynamic properties of the scandium germanides ScGe2 and ScGe

The thermodynamic properties of alloys in the Sc-Ge system have been little studied. Only investigations of the enthalpy of formation of the liquid alloys are known [i], and measurements of the heat capacity of ScsGe 3 at low temperatures (12-300K) [2]. Besides this germanide, in the Sc-Ge system, according to the phase diagram constructed with the assistance of one of the present authors [3] several other intermediate phases appear ScGe2, ScGe, Sc11Ge10, and ScsGe 4. None of these phases possesses an appreciable range of homogeneity.

Polythermal and isothermal sections of the system titanium-copper-silver. Part II

ConclusionsThe method of thermal analysis was used to study the structure of three polythermal sections of the constitution diagram of the system titanium-copper-silver: at 5 at.% Ag, at 60 at.% Ag, and the radial section TiAg (η)-Cu. On the basis of these polythermal sections and of the liquidus surface, isothermal sections of the system titanium-copper-silver at 1300, 1005, 960, and 900°C have been constructed. The processes taking place in the ternary system titanium-copper-silver and in the bounding binary systems have been represented in the form of a diagram.