Zhang Dongjiang, Yu Rui, Feng Xuelei, Guo Xuncheng, Yang Yongkang, Xu Xiqing
Xi'an Modern Control Technology Research Institute, Xi'an 710065, China.
School of Materials Science & Engineering, Chang'an University, Xi'an 710061, China.
Materials (Basel). 2023 Aug 17;16(16):5652. doi: 10.3390/ma16165652.
In this work, AlO nanoceramics were prepared by spark plasma sintering of amorphous powders and polycrystalline powders with similar particle sizes. Effective comparisons of sintering processes and ultimate products depending on starting powder conditions were explored. To ensure near-full density higher than 98% of the AlO nanoceramics, the threshold temperature in SPS is 1450 °C for polycrystalline AlO powders and 1300 °C for amorphous powders. The low SPS temperature for amorphous powders is attributed to the metastable state with high free energy of amorphous powders. The AlO nanoceramics prepared by amorphous powders display a mean grain size of 170 nm, and superior mechanical properties, including high bending strength of 870 MPa, Vickers hardness of 20.5 GPa and fracture toughness of 4.3 MPa∙m. Furthermore, the AlO nanoceramics prepared by amorphous powders showed a larger dynamic strength and dynamic strain. The toughening mechanism with predominant transgranular fracture is explained based on the separation of quasi-boundaries.
在这项工作中，通过对粒径相似的非晶态粉末和多晶态粉末进行放电等离子烧结制备了AlO纳米陶瓷。探索了根据起始粉末条件对烧结过程和最终产物进行有效的比较。为确保AlO纳米陶瓷的密度接近全密度且高于98%，对于多晶态AlO粉末，放电等离子烧结中的阈值温度为1450℃，对于非晶态粉末则为1300℃。非晶态粉末的放电等离子烧结温度较低归因于非晶态粉末具有高自由能的亚稳态。由非晶态粉末制备的AlO纳米陶瓷的平均晶粒尺寸为170nm，并且具有优异的力学性能，包括870MPa的高抗弯强度、20.5GPa的维氏硬度和4.3MPa∙m的断裂韧性。此外，由非晶态粉末制备的AlO纳米陶瓷表现出更大的动态强度和动态应变。基于准边界的分离解释了以穿晶断裂为主的增韧机制。
