(北京工業(yè)大學 材料科學與工程學院,
新型功能材料教育部重點實驗室， 北京 100022)
摘 要: 采用高能球磨法制備了Co納米晶粉體， 平均晶粒尺寸為(17±3) nm。 設計了一系列寬溫度范圍的退火實驗， 考察純Co納米晶粉體的晶粒長大行為。 實驗發(fā)現， 低溫區(qū)和高溫區(qū)的晶粒長大動力學有明顯差異， 而在中溫區(qū)出現不連續(xù)晶粒長大特征。 高分辨透射電鏡觀測表明： 在低溫區(qū)， 納米晶中存在較大比例的小角度納米晶界， 而在高溫區(qū)則基本為典型的大角度晶界。 結合納米晶熱力學計算和DSC分析， 認為納米晶粒在中溫區(qū)的突發(fā)迅速長大是由殘余儲存能作為附加驅動力激發(fā)的動力學過程， 其主導機制是通過相鄰小角度位向差的納米晶粒的轉動而實現晶粒快速粗化。
關鍵字: 金屬納米晶； 不連續(xù)晶粒長大； 納米晶界； 儲存能
（ College of Materials Science and Engineering,
Key Laboratory of Functional Materials of Education Ministry,
Beijing University of Technology, Beijing 100022, China）
Abstract: Grain growth in highly pure nanocrystalline Co powders prepared by high-energy ball milling with the average grain size of about (17±3) nm was investigated by a series of annealing experiments. The characteristics of discontinuous grain growth are found in the transition zone in the intermediate temperature region. The TEM observations show that there are a number of low-angle nanograin boundaries at low temperatures, whereas mostly typical high-angle grain boundaries at high temperatures. It is proposed that, the rapid grain growth occurring in the intermediate temperature region is resulted from enhanced grain growth promoted by the stored energy as an extra driving force, and through a particular dominant mechanism of nanograin rotations.
Key words: metal nanocrystalline powder; discontinuous grain growth; nanograin boundary; stored energy
