(1. 北京有色金屬研究總院有色金屬材料制備加工國家重點(diǎn)實(shí)驗(yàn)室，北京 100088；
2. 北京有色金屬研究總院有色金屬加工中心，北京 100088)
摘 要: 對(duì)Al-Cu-Li合金進(jìn)行溫度300~500 ℃、應(yīng)變速率0.001~10 s-1的等溫?zé)釅嚎s，分析合金的流變行為；結(jié)合TEM和EBSD研究合金熱變形過程中的組織演變。結(jié)果表明：合金流變曲線分為3個(gè)階段：加工硬化階段、過渡階段和穩(wěn)態(tài)變形階段；變形溫度越高，流變應(yīng)力達(dá)到動(dòng)態(tài)平衡所需應(yīng)變量越小。基于應(yīng)變硬化率(θ)與流變應(yīng)力(σ)之間的關(guān)系，確定動(dòng)態(tài)再結(jié)晶的臨界應(yīng)變(εc)；不同熱變形條件下的臨界應(yīng)變(εc)與峰值應(yīng)變(εp)之比為0.30342~0.92828；臨界應(yīng)力(σc)與峰值應(yīng)變(σp)之比為0.88492~0.99782。引入最大軟化率應(yīng)變(ε*)和中間變量Z/A，建立εc和ε*與Z/A的關(guān)系表達(dá)式。構(gòu)建Al-Cu-Li合金動(dòng)態(tài)再結(jié)晶動(dòng)力學(xué)模型，模型表明，溫度越高或應(yīng)變速率越低，越有利于促進(jìn)動(dòng)態(tài)再結(jié)晶分?jǐn)?shù)的增加；顯微組織分析結(jié)果與模型預(yù)測規(guī)律一致。Al-Cu-Li合金動(dòng)態(tài)再結(jié)晶形核機(jī)制主要為晶界突出形核機(jī)制、亞晶合并長大機(jī)制以及粒子促進(jìn)形核機(jī)制，隨溫度升高和應(yīng)變速率的降低，晶內(nèi)亞晶合并長大機(jī)制得到加強(qiáng)。
關(guān)鍵字: Al-Cu-Li合金；臨界應(yīng)變；動(dòng)態(tài)再結(jié)晶模型；再結(jié)晶形核機(jī)制
（1. State Key Laboratory of Nonferrous Metals and Processes, General Research Institute for Nonferrous Metals,
Beijing 100088, China;
2. Nonferrous Metals Processing Division, General Research Institute for Nonferrous Metals, Beijing 100088, China）
Abstract:The flow behaviors of Al-Cu-Li alloy were investigated by isothermal hot compressive tests, which were carried out at the deformation temperature range of 300-500 ℃, and strain rate of 0.001-10 s-1. Microstructure evolution process was studied by TEM and EBSD analysis. The results show that flow curve can be divided into three stages: work hardening stage, transition stage and steady stage. The higher the deformation temperature is, the smaller strain required for dynamic balance of flow stress is. According to the flow behaviors of Al-Cu-Li alloy, critical strain (εc) of dynamic recrystallization is determined based on the relationship of strain hardening rate and flow stress. Under different hot deformation conditions, the ratio of critical strain (εc) to the peak strain (εp) is 0.30342-0.92828, and the ratio of the critical stress (σc) to the peak stress (σp) is 0.88492-0.99782. Introducing the strain for maximum softening rate strain (ε*) and intermediate variable (Z/A), and the relationships among εc, ε* and Z/A are obtained. Dynamic recrystallization kinetics model is identified to express the evolution of dynamic recrystallization. The higher the deformation temperature or the lower strain rate, the more beneficial to increase the dynamic recrystallization fraction. Predicted rules by proposed model show a good agreement with microstructure analysis results. Dynamic recrystallization nucleation mechanisms are constituted of grain boundaries bulging nucleation, subgrain rotated induced nucleation and particle stimulated nucleation mechanism. Subgrain rotated induced nucleation transgranular is strengthened with increasing temperature and decreasing strain rate.
Key words: Al-Cu-Li alloy; critical strain; dynamic recrystallization model; recrystallization nucleation mechanism
