(中南大學(xué) 材料科學(xué)與工程學(xué)院， 長(zhǎng)沙 410083)
摘 要: 借助力學(xué)性能實(shí)驗(yàn)、 金相顯微鏡和透射電鏡等手段研究了純鉭的加工硬化速率。 研究結(jié)果表明： 純鉭的宏觀加工硬化速率比較低。 通過(guò)TEM觀察， 發(fā)現(xiàn)變形95％后， 純鉭的位錯(cuò)密度都不是很高， 存在有位錯(cuò)胞亞結(jié)構(gòu)。 其原因可能是因?yàn)殂g的層錯(cuò)能高， 位錯(cuò)容易交滑移， 使位錯(cuò)密度降低。 根據(jù)林位錯(cuò)硬化理論， 也可以認(rèn)為， 鉭在室溫下塑性變形時(shí)， 滑移系主要為｛110｝〈111〉， 次滑移系的激活比較少， 因此穿過(guò)主滑移系的林位錯(cuò)密度比較低， 位錯(cuò)之間相互作用少， 導(dǎo)致鉭的加工硬化速率低。
關(guān)鍵字: 鉭； 加工硬化； 位錯(cuò)密度
microstructure of tantalum
（School of Materials Science and Engineering, Central South University,
Changsha 410083, China）
Abstract: The work hardening rate of pure tantalum was studied by tension test, optical microscope and TEM. The results show that the work hardening rate of pure tantalum is low. TEM analysis indicates that the dislocation density of pure tantalum is not high and dislocation cells occur after 95% cold rolling reduction. Because the stacking fault energy (SFC) of tantalum is high, the dislocation cross slips easily which can lower the dislocation density. On the other hand, according to the tree dislocation theory, it is assumed that when pure tantalum is deformed at room temperature, the slip system is mainly｛110｝〈111〉, while the secondary slip systems are seldom activated. So the density of tree dislocation penetrating the main slip plane is low and the interaction between dislocations is weak, which leads to low work hardening rate of pure tantalum.
Key words: tantalum; work hardening; dislocation density
