(1. 中南大學(xué) 材料科學(xué)與工程學(xué)院，長沙 410083；
2. Institute of Materials Science, Lausanne Federal Institute of Technology, Lausanne CH-1015, Switzerland)
摘 要: 采用機(jī)械合金化法制備納米Cu-10%Nb合金，通過顯微硬度測量以及高分辨透射電鏡觀察，對該合金粉末在室溫球磨過程中的微觀結(jié)構(gòu)演變和形變孿生特性進(jìn)行研究；利用局部應(yīng)力集中模型分析形變孿晶的形核機(jī)制。結(jié)果表明：隨著球磨時間的增加，該合金硬度(HV)不斷升高，球磨120 h后可達(dá)4.8 GPa；該合金在球磨初期以位錯胞結(jié)構(gòu)為主；球磨50 h后，Cu平均晶粒尺寸減小至約50 nm，部分區(qū)域出現(xiàn)納米形變孿晶；繼續(xù)增加球磨時間，孿晶數(shù)量增加，孿晶界強化效果顯著；由于孿生將促進(jìn)納米晶粒的進(jìn)一步細(xì)化，球磨120 h后，納米晶尺寸減小到20 nm以下。
關(guān)鍵字: Cu-Nb合金；機(jī)械合金化；形變孿晶；孿晶界強化；納米材料
Cu-Nb alloy powders
（1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. Institute of Materials Science, Lausanne Federal Institute of Technology, Lausanne CH-1015, Switzerland）
Abstract:The microstructure evolution and deformation twinning characteristics of nanocrystalline Cu-10%Nb alloy during mechanical alloying (MA) were investigated by microhardness measurements, transmission electron microscopy (TEM) and high resolution TEM (HRTEM) observation. A local stress concentration model was proposed to explain the deformation twin nucleation mechanism of Cu-Nb alloy. The results show that the Vickers microhardness of the powders increases gradually with the increase of milling time, and reaches 4.8 GPa after 120 h milling. The main structure of the powders is the dislocation cells in the initial milling. After 50 h milling, the average Cu grain size decreases to about 50 nm, and nano-deformation twins begin to form in some regions. With the continued increase of the milling time, the number of twin increases, and the twin boundary strengthening enhances accordingly. Due to the deformation twinning will contribute to further refine the nano-grains, after 120 h milling, the nano-crystalline size decreases to below 20 nm.
Key words: Cu-Nb alloy; mechanical alloying; deformation twinning; twin boundary strengthening; nanostructured material
