The effect of yttrium oxide on the sintering behavior and hardness of tungsten

Abstract

In this study, the relative density and hardness of Y2O3 dispersed tungsten alloy were investigated as functions of the Y2O3 content and sintering temperature. The sintering temperature and the amount of the second phase were varied from 1800 to 2500 o C and 0 to 2.0 weight pct, respectively. The relative density of the alloys is higher than that of pure tungsten in the range from 2000 to 2500 o C, whereas the density is lower at 1800 o C. As the Y2O3 content increases, the sintered density increases at a given temperature. The transition temperature (Ttr), where the relative density of the alloys exceeds that of pure tungsten, is reduced with increased Y2O3 particle content. In order to examine the effect of the second phase on the mechanical property, the hardness of pure tungsten and the alloys are measured. The hardness is mainly dependent upon the relative density of the alloys, rather than the amount of the second phase and tungsten grain size. The relationship between hardness and density is discussed according to the plasticity theory of porous materials.

Mechanical properties of Y2O3-doped W–Ti alloys

“…The hardness values for pure W are similar to those reported in [21] for sintered W with densities in the range 87 92%. They are, obviously, much lower than those measured in fully dense wrought W (which can reach 4.5 GPa [22]) whose yield strength has been increased by plastic deformation (extrusion, swaging, etc.).…”

“…For instance, it has been shown that La 2 O 3 dispersion or Al K Si doping can signifi cantly improve the mechanical strength and the RCT of W, but it appears that the DBTT cannot be lowered this way [6,12 14]. Y 2 O 3 additions strengthen W and increase its creep resistance [15,16] and it has recently been reported that Y 2 O 3 doped W pro duced by powder metallurgy (PM) and consolidated by hot iso static pressing (HIP) achieves certain ductility at 400 °C [17]. In addition, this Y 2 O 3 doped W presented enhanced mechanical properties and a remarkable oxidation resistance at high tempera tures, in comparison to W produced by the same procedure [17].…”

Investigation of microstructure and mechanical properties of W–Y and W–Y2O3 materials fabricated by powder metallurgy method

“…La 2 O 3 -dispersed W exhibits high creep resistance and improves tensile strength at high temperature but its hygroscopic property limits its wide use [7]. On the other hand, it was reported that dispersion of Y 2 O 3 particles in W matrix enhances the high temperature strength irradiation and creep resistance [8][9][10][11]. Moreover, in contrast to ThO 2 or La 2 O 3 , it does not represent any hazardous effects.…”

Effects of rare earth oxide additive on surface and tribological properties of polyimide composites

“…Rare earth elements with special electronic structures and high chemical activity tend to coordinate and react with functional groups of polymers such as -SO2-, C=O, C-OH, C=O [46][47][48]. Research results have shown that a small loading of rare earth oxides such as cerium oxide, yttrium oxide and lanthanum dioxide in alloys can effectively increase the hardness thereby to deliver excellent tribological properties [49][50][51].…”