Damage and microstructure evolution of yttria particle-reinforced tungsten plates under laser thermal shock
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摘要: 采用粉末冶金技术结合轧制工艺制备不同压下量的氧化钇颗粒增强钨板,并对不同温度等温退火实验得到的不同再结晶体积分数的样品进行瞬态激光热冲击实验,研究长期稳态热负荷引起的再结晶与瞬态热冲击的协同作用下的表面损伤和显微组织演化。在瞬态热冲击的作用下,样品表面发生开裂、熔化等损伤,再结晶过程会加速裂纹变宽、熔化区域变大,降低了材料抵抗瞬态热负荷的能力。67%轧制量的样品明显比50%轧制量样品在同功率密度下的损伤程度低,前者具有较好的抗热冲击性。且两种样品熔化区的晶粒主要由大量柱状晶组成,其柱状晶晶粒的大小与之下面的初始基体晶粒有很大关系,轧制态样品熔化区中的柱状晶晶粒较细且多,而完全再结晶样品的晶粒较粗。
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关键词:
Abstract: Yttria particle-reinforced tungsten plates with different thickness reduction are prepared by powder metallurgy technology combined with rolling process. The transient laser thermal shock experiments are carried out on the samples’ surface with different recrystallization volume fraction which are obtained at different temperatures annealing process, aimed to investigate the surface damage and microstructure evolution under the synergistic effect of recrystallization caused by long-term steady-state heat load and transient thermal shock. Cracks, melting and other damages occur on the sample surface because of the action of thermal shock loading. Moreover, the recrystallization process will accelerate the widening of cracks and the enlargement of melting area, which greatly reduces the ability of the material to resist transient heat loading. The damage level of the samples with 67% thickness reduction is obviously lower than that with 50% thickness reduction under the same power density, and the former has better thermal shock resistance. Both the molten zone is composed by the columnar grains, the width of the columnar grains is associated with the grain size of the initial matrix below, and the columnar grains formed in rolled samples are finer and numerous, while those of the fully recrystallized samples are coarser.-
Key words:
- powder metallurgy /
- tungsten /
- yttria /
- thermal shock /
- surface damage /
- microstructure
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