Investigation of Material Problems for High Temperature, High Power Space Energy-Conversion Systems

摘要

The final report has been divided in six sections. The first one is an introduction. In the second section, the theory of dilute-solutions ultralloys from tungsten sintering with special eutectic applications is presented, together with a comprehensive literature survey including 95 references. In the third one, the results for the work function evaluation of tungsten-rhenium sintered alloys, obtained by using thermionic emission microscopy, are presented. The influence of rhenium content in the range 3 percent to 30 percent, and temperature, between 1946 to 2339K in the work function are reported. The fourth section includes the determination of effective work function, normal spectral emissivity, recrystallization temperature and microhardness of tungsten-rhenium and tungsten-rhenium-thoriated alloys, in the temperature range between 1400 to 2500K. Section No. 5 summarizes the research on the influence of heating time, temperature and alloying content of rhenium in the work function of tungsten alloys as determined in the Vacuum Emission vehicle. Finally, in the last section, the mechanical properties of tungsten-30 percent rhenium were investigated by using an Instron tensile testing equipment with a high temperature, ultrahigh vacuum system. The relationship between the normalized Young's modulus, ultimate tensile strength, yield strength, elongation and test temperature was examined. (Author)