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以自悬浮定向流技术制备的纳米Al粉末为原料,采用真空热压技术制得了平均晶粒尺寸为90~123 nm的纳米晶Al块体。通过XRD、SEM和显微硬度测试研究了热压温度和热压压力对纳米晶Al的微观结构和显微硬度的影响。结果表明:各纳米晶Al块体的显微硬度分布在0.8~1.98 GPa范围内。不同的热压温度和热压压力范围内,不同的固结机理主导着纳米晶Al的致密化过程。由于受致密度、晶粒尺寸、微观应变、杂质氧化铝结构等因素的共同影响,纳米晶Al的显微硬度随热压温度的升高先增大后减小,随热压压力的增大表现出先快后慢的增长。低密度块体表现出明显的压痕尺寸效应,而高密度块体并没有表现出这种现象。
Nanostructured Al bulk with average grain size of 90 ~ 123 nm was prepared by vacuum hot pressing using nano-Al powder prepared by suspension directional flow technique. The effects of hot pressing temperature and hot pressing pressure on the microstructure and microhardness of nanocrystalline Al were investigated by XRD, SEM and microhardness tests. The results show that the microhardness of Al nanocrystals is 0.8 ~ 1.98 GPa. Different hot-pressing temperature and hot-pressing pressure range, different consolidation mechanisms dominate the densification process of nanocrystalline Al. Due to the influence of density, grain size, micro-strain and impurity aluminum oxide structure, the microhardness of nano-Al first increases and then decreases with the increase of hot-pressing temperature. With the increase of hot-pressing pressure, Fast and slow growth. Low-density blocks show significant indentation size effects, whereas high-density blocks do not exhibit this phenomenon.