(中南大學(xué) 粉末冶金國家重點(diǎn)實(shí)驗(yàn)室，長沙 410083)
摘 要: 采用透射電鏡研究Er和Yb元素對(duì)二元Al-Mg合金位錯(cuò)分布組態(tài)的影響。研究結(jié)果表明：二元Al-Mg合金擠壓態(tài)的位錯(cuò)組態(tài)呈典型的“Taylor晶格”分布，但經(jīng)拉伸變形至斷裂后，合金中儲(chǔ)存的高應(yīng)變能可以抵消Mg原子對(duì)位錯(cuò)運(yùn)動(dòng)的阻礙作用，使部分位錯(cuò)發(fā)生束集而產(chǎn)生交滑移，最終形成胞狀組織。添加Er元素不改變Al-Mg合金的位錯(cuò)組態(tài)，無論是經(jīng)擠壓還是經(jīng)拉伸變形至斷裂后，含Er的Al-Mg合金均具有與二元Al-Mg合金類似的位錯(cuò)分布組態(tài)。添加Yb元素可明顯地改變Al-Mg合金的位錯(cuò)分布組態(tài)。即使在變形量較小的擠壓態(tài)，位錯(cuò)也不呈準(zhǔn)均勻的 “Taylor晶格”分布，而是表現(xiàn)出胞狀組織的特征。當(dāng)添加0.3%(質(zhì)量分?jǐn)?shù))的Yb時(shí)，Al-Mg合金中形成了高密度位錯(cuò)墻；而當(dāng)添加1.0%的Yb時(shí)，合金中形成了明顯的胞狀組織。Yb原子通過與Mg和Al原子形成脆性化合物，降低了Mg在基體中的固溶度，從而抑制Mg原子對(duì)位錯(cuò)運(yùn)動(dòng)的阻礙作用。
關(guān)鍵字: Al-Mg合金；位錯(cuò)組態(tài)；Taylor 晶格；胞狀組織
binary Al-Mg alloy
（State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China）
Abstract:The effects of Er and Yb elements on the dislocation distributions of a binary Al-Mg alloy were studied using a transmission electron microscope (TEM). It is shown that the as-extruded dislocation distributions of the binary Al-Mg alloy show typical “Taylor lattice” configurations, while the dislocation distributions of the binary Al-Mg alloy after the tensile testing to fracture show cell structures since the stored high deformation energy can effectively decrease the inhibition of Mg atoms on the dislocation movements. The addition of Er element cannot change the dislocation distributions of the Al-Mg alloy. The dislocation distributions in Er-containing alloy show similar characteristics to the binary Al-Mg alloy, no matter whether the alloy is in extruded state or after tensile testing to fracture. However, the addition of Yb element can obviously change the dislocation distributions of the Al-Mg alloy. Even under low deformation degree, such as in the as-extruded stage, the dislocation distributions show the features of cell structure, instead of the quasi-uniform distributed “Taylor lattice”. When 0.3%(mass fraction) Yb is added into the alloy, the dislocation walls with high density dislocations are formed in the matrix, and when 1.0% Yb is added into the alloy, the cell structures are formed obviously in the alloy. Yb atoms, combined with Mg and Al atoms, form brittle compounds in the alloy, decrease the solid solution degree of the Mg atoms in the Al matrix, and thus decrease the inhibition of the Mg atoms on the dislocation movements.
Key words: Al-Mg alloy; dislocation configuration, Taylor lattice; cell structure
