氧化镧增强钨合金高能电子束烧蚀研究

Study on High Energy Electron Beam Ablation of Tungsten Alloy Reinforced by Rare Earth

对W-La2O3合金在入射电子束不同能量密度辐照下的烧蚀性能进行了研究。结果表明:随着烧蚀时间的延长,表面温度上升,温度与烧蚀时间的关系近似呈线性,热流密度增加,表面温度在相同时间内上升幅度增大。在热流密度为0.5MW/m2烧蚀时,样品完好。热流密度为3MW/m2时,表面无宏观裂纹,试样表层几个微米内出现微裂纹,微裂纹沿钨晶粒边界交织成网状分布。热流密度为5MW/m2时,试样表层约十几个微米深度内出现熔融,基体晶粒组织无变化。当热流密度增加至8MW/m2时,试样熔化深度过半,内部较大的热应力导致试样扭曲变形失效破坏。W-La2O3合金抗烧蚀性能较好,热流密度增加到5MW/m2时,烧蚀率很小且变化不大,随着入射电子束热流密度增加,抗烧蚀性能下降,烧蚀率逐渐增大,当热流密度增加到8MW/m2时,质量烧蚀率达到2%。

The ablation properties of tungsten alloy reinforced by La2 O3 particles were measured under high energy electron beam at different energy flux. Results reveal that the surface temperature rises with time extending, and temperature has a linear relation with ablation time. The sample keeps intact at heat load flux of 0. 5MW/m^2. When heat load flux increases to 3MW/m^2 , there are microcracks on surface in several micrometers depth. Microcracks complect to a reticulation along the tungsten grain boundaries. The surface layer melts with a depth of about 10- 20μm at heat load flux of 5MW/m^2 , but the grain structures beneath the layer have no change. At heat load flux of 8MW/m^2 , the sample melts severely more than half of the height, and thermal stress distorts the sample to break- age. W-La20a has an excellent ablation resistance, the mass ablation rate still keeps low when heat load flux increa- ses to 5MW/m^2. But ablation resistance declines when heat load flux increasing, the mass ablation rate increase to 2% at heat load flux of 8MW/m^2.