COMPOSITION, STRUCTURE, AND PROPERTIES OF SINTERED SILICON-CONTAINING TITANIUM ALLOYS

Abstract

The main factors limiting the application of high-temperature creep-rupture resistant titanium alloys synthesized from powder components by pressing and subsequent vacuum sintering for the manufacture of parts for gas turbine engines are analyzed. The method for synthesizing the VT1-0 alloy and the alloy whose chemical and composition corresponds to the high-temperature creep-rupture resistant VT8 alloy is described. Their chemical and phase composition, strength characteristics, hardness, and distribution of doping elements are examined. Upon analysis of the composition, structure, and properties of the samples produced from test alloys synthesized from PT5 titanium powders with different particle sizes by powder metallurgy methods, it was concluded that semi-finished products could be produced from the VT1-0 and VT8 titanium alloys. The effect of the particle size of the titanium matrix on the chemical composition of the synthesized alloys is studied. The chemical composition of the test alloy complies with the industry standard for semi-finished products of high-temperature creep-rupture resistant titanium alloys. The influence of the fraction composition of titanium powder on the strength and hardness, as well as residual porosity, of the synthesized alloys is established. It is shown that, regardless of the particle size of the powder mixture matrix (from 40 to 400 µm), the strength, ductility, and hardness of the VT8 test alloy do not comply with the requirements of standards OST 90002–70 and OST 90006–70, which govern these properties for bars and blanks of gas turbine engine blades. It is concluded that a series of measures intended to eliminate the residual porosity and form the blade material structure are required to improve the strength properties.