SPS烧结W-TaC的耐瞬态热冲击性能

Transient Thermal Shock Performance of Sintered W-TaC by SPS

通过高能球磨方法制备了系列W-TaC混合粉末,采用放电等离子体烧结(SPS)制备出弥散强化W-TaC样品,并对W-TaC样品的密度、硬度和微观组织进行了分析。利用60 k W电子束材料测试平台(EMS-60)对烧结W-TaC的耐瞬态热冲击性能进行测试,分别模拟了等离子体破裂和边缘局域模2种热负荷。实验后通过扫描电镜观察了样品加载区域的裂纹及熔化情况,通过透射电镜观察分析了材料的微结构特征。结果表明:W-TaC样品在热负荷作用下可以经受功率密度为740 MW/m^2、5 ms的热冲击而不产生裂纹,但在功率密度为550 MW/m^2、100次1 ms的热疲劳下会产生疲劳微裂纹。SEM和TEM分析表明,TaC颗粒在钨晶粒内和晶粒间都有存在,而且TaC会与W形成共格相界和半共格晶界从而增强钨合金的强度。

Dispersion strengthened tungsten with tantalum carbide were prepared by Spark Plasma Sintering（SPS）. High heat flux tests were performed with the electron beam device EMS-60（60 k W Electron-beam Material-test Scenario）. The polished tungsten surfaces were exposed to single shot disruption-like and repetitive ELM-like thermal shock loads at various absorbed energy densities. The thermal shock-induced damages were analyzed by scanning electron microscope and the microstructure was observed by transmission electron microscope. The result show that no cracks are detected on the tungsten surface when the sample is exposed to single shot thermal shock with absorbed energy density at 740 MW/m^2; while cracks appear when the sample is exposed to repetitive thermal shock with absorbed power density at 550 MW/m^2. SEM and TEM images indicate that TaC particles disperse in tungsten grains interior including both intragranular and intergranular. Thus strengthening phase boundaries through coherent structure and strengthening grain boundaries through semi-coherent structure lead to excellent strength of W-TaC alloy plate.