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首页> 外文期刊>Materials Science and Engineering >Effects of La_2O_3 and Nb_2O_5 dopants on the microstructural development and fracture toughness of Al_2O_3 ceramic
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Effects of La_2O_3 and Nb_2O_5 dopants on the microstructural development and fracture toughness of Al_2O_3 ceramic

机译：La_2O_3和Nb_2O_5掺杂对Al_2O_3陶瓷显微组织发展和断裂韧性的影响。

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Previous research has shown that the inherently low fracture toughness of Al2O3ceramics can be improved by in situ growth of a small volume fraction of anisotropic grains. In this study, 7.5La2O3-5Nb2O5-87.5Al2O3(volume percent) composite ceramics were fabricated by microwave sintering, with the intention of tailoring alumina microstructural development to improve fracture toughness. The effects of sintering temperature and holding time on density and fracture toughness of the composite were investigated, and the growth and toughening mechanisms of columnar grains were discussed. The optimal sintering conditions for La2O3/Nb2O5doped Al2O3ceramics occurred at 1500 °C for 30 min, which is at least 100 °C lower than that of dense Al2O3. The phases present in the 7.5La2O3-5Nb2O5-87.5Al2O3included in situ columnar grains of α-Al2O3and LaAl11O18, and equiaxed grains of monoclinic LaNbO4. It is shown that a liquid phase induced the growth of columnar grains. The fracture toughness of the 7.5La2O3-5Nb2O5-87.5Al2O3composite ceramic was improved by 116% compared with that of Al2O3, due to the anisotropic grain growth that enabled toughening mechanisms such as grain pull-out, crack deflection, crack branching, crack bridging, and domain switching.
机译：先前的研究表明，可以通过原位生长少量的各向异性晶粒来改善Al2O3陶瓷固有的低断裂韧性。本研究采用微波烧结法制备了7.5La2O3-5Nb2O5-87.5Al2O3（体积百分比）复合陶瓷，旨在适应氧化铝的微观组织发展，以提高断裂韧性。研究了烧结温度和保温时间对复合材料密度和断裂韧性的影响，探讨了柱状晶粒的生长和增韧机理。 La2O3 / Nb2O5掺杂的Al2O3陶瓷的最佳烧结条件发生在1500 C下30 min，比致密Al2O3至少低100C。 7.5La2O3-5Nb2O5-87.5Al2O3中存在的相包括α-Al2O3和LaAl11O18的原位柱状晶粒，以及单斜LaNbO4的等轴晶粒。结果表明，液相诱导了柱状晶粒的生长。 7.5La2O3-5Nb2O5-87.5Al2O3复合陶瓷的断裂韧性比Al2O3提高了116％，这是由于各向异性的晶粒长大使得诸如晶粒拉出，裂纹偏转，裂纹分支，裂纹桥接，和域切换。

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