(1. 中南大學(xué) 材料科學(xué)與工程學(xué)院，長沙 410083；
2. 中國鋁業(yè)公司，北京 100082)
摘 要: 利用光學(xué)顯微鏡(OM)、掃描電子顯微鏡(SEM)和透射電子顯微鏡(TEM)研究大變形冷軋Al-6Mg-0.4Mn- 0.25Sc-0.1Zr(質(zhì)量分?jǐn)?shù)，%)合金在不同穩(wěn)定化退火過程中的組織演變及單軸拉伸斷裂行為。結(jié)果表明：在大變形冷軋過程中，彌散分布的納米級Al3(Sc,Zr)粒子阻礙位錯運(yùn)動和晶界遷移，位錯密度顯著增加。高密度的位錯纏結(jié)誘發(fā)局部不均勻變形，形成大量剪切變形帶。冷軋狀態(tài)下，合金組織分布不均勻，剪切帶區(qū)域位錯密度較大，變形儲能較高，在單軸拉應(yīng)力狀態(tài)下，合金沿著剪切帶方向發(fā)生剪切斷裂。在穩(wěn)定化退火過程中，剪切變形帶中優(yōu)先發(fā)生形核與晶粒長大。隨著穩(wěn)定化退火溫度的不斷提高，亞晶發(fā)生合并長大，剪切變形組織逐漸消失，合金的斷裂行為由剪切斷裂轉(zhuǎn)變?yōu)榛旌闲晚g性斷裂。經(jīng)過高溫穩(wěn)定化退火處理后，部分Al3(Sc,Zr)粒子發(fā)生粗化，析出相彌散強(qiáng)化作用減弱，少量粗大粒子轉(zhuǎn)變?yōu)榱鸭y源，合金強(qiáng)度逐漸減弱。
關(guān)鍵字: Al-Mg-Sc-Zr合金; 穩(wěn)定化退火; 再結(jié)晶; Al3(Sc,Zr)粒子; 力學(xué)性能
（1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. Aluminum Corporation of China, Beijing 100082, China）
Abstract:The microstructure evolution and uniaxial testing fracture behaviors of Al-6Mg-0.4Mn-0.25Sc-0.1Zr (mass fraction, %) alloys after high strain cold rolling were investigated during annealing treatment by optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results indicate that the presence of nano-scale Al3(Sc,Zr) particles will increase the dislocation density due to its great pinning effect on migration of dislocations and grain boundaries during cold rolling. These dislocation tangles induce the occurrence of inhomogeneous deformation in local area and promote the formation of shear bands. When loaded with uniaxial tensile stress, the as cold-rolled specimens tend to fracture along shear bands in which the dislocation density, as well as deformed store energy is higher than that in other regions. The nucleation and growth of new grains occur preferentially in shear bands during stabilizing annealing treatment. The annealed specimens perform a hybrid ductile fracture behavior with the coarsening of subgrains and elimination of shear bands when elevating the annealing temperatures. Meanwhile, the precipitation strengthening effect of Al3(Sc,Zr) particles diminishes gradually due to the coarsening of some particles after high-temperature stabilizing annealing. Some over-size particles even turn to be crack initiation and the mechanical properties of alloys decrease.
Key words: Al-Mg-Sc-Zr alloy; stabilizing annealing; recrystallization; Al3(Sc,Zr) particles; mechanical property
