Effect of Al-Ti-C system master alloy high energy synthesis on efficiency of Ni based superalloy inoculation
The possibility of high energy synthesis of Ti–Al–C system powder grain refiner by using high voltage electric discharges for treatment of powder mixtures of 75 % Ti + 25 % Al and 85 % Ti + 15 % Al composition in kerosene with subsequent briquetting by spark plasma sintering is shown in present work. It is found out that high voltage electric discharge treatment of powders leads to the increase of dispersity as well as to synthesis of new carbon containing phases during chemical interaction between system components and products of working hydrocarbon liquid destruction. The possibility of controlling this process by changing initial composition of powders, specific treatment energy and spatial distribution of plasma formations by changing electrode system type is shown. It is also shown that changing master alloy synthesis parameters allows controlling inoculation efficiency. Thereby it is possible to achieve surface or volumetric inoculation, so selective increasing of plastic or strength properties of Ni-based cast superalloys becomes possible. Introduction of 0.01 % of synthesized grain refiner during the casting of SM88U (СМ88У) superalloy allows decreasing mean grain size from 1…2 mm to 0.2…0.5 mm. Tensile strength of inoculated superalloy at the temperature of 900˚С was 68 MPa while their stress rupture strength increased by 20 % in average. Composition and properties of inoculated alloys comply with standard technical documentation, which allows their usage for the
production of gas turbines blades.