超细/纳米W-La2O3复合粉末的制备及烧结致密化行为研究

摘要

Ultrafineano W-La2O3 composite powder with high sintering activity are prepared by sol-gel method. The structures and densification behavior of W-La2O3 composite powder are studied by SEM, XRD and BET methods. The results show that the particle size of ultrafineano W-La2O3 composite powders is fine. The composite powder becomes more refined with the increasing La2O3 content. The particle size and grain size of W-0.7La composite powder are 100 nm and 56 nm respectively. The inhibition effect of La2O3 second phase particles on grain boundary pinning and the promoting effect of powder refinement are coexistent in the densification process. Under low temperature condition, the inhibition effect is dominant. The relative density and micro-hardness improves with the increasing sintering temperature. the second phase particles grow and dispersion strengthening and grain refinement effect decrease at high temperature.%采用溶胶-喷雾干燥-煅烧还原方法制备具有高烧结活性的超细/纳米W-La2O3复合粉末，烧结制备W-La2O3复合材料。通过SEM、XRD对粉末的制备、烧结致密化行为进行分析和表征，研究表明：溶胶-喷雾干燥-煅烧还原方法制备的超细/纳米W-La2O3复合粉末粒度均匀细小，随La2O3含量的增加有明显细化趋势，W-0.7La复合粉末粒度与晶粒尺寸达到0.1μm和56 nm；致密化过程中La2O3第二相粒子表现为晶界钉扎的抑制作用与粉末细化的促进作用共有，低温条件下抑制作用占主导；随烧结温度的提高，材料相对密度增加，显微硬度提高；烧结温度过高时，第二相粒子迁移长大，弥散强化与晶粒细化作用减弱。