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Al-Cu-Li-Mg-Mn-Zn-Ag合金的熱變形流變行為與本構(gòu)方程
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更新時(shí)間：2015-09-16
采用等溫?zé)釅嚎s測試和TEM分析研究鋁鋰合金的流變行為與組織演化規(guī)律。
Al-Cu-Li-Mg-Mn-Zn-Ag合金的熱變形流變行為與本構(gòu)方程Flow behavior and constitutive equations of Al-Cu-Li-Mg-Mn-Zn-Ag alloy during isothermal compression
采用等溫?zé)釅嚎s測試和TEM分析研究鋁鋰合金的流變行為與組織演化規(guī)律。結(jié)果表明：合金的熱塑性變形過程受熱激活控制，當(dāng)變形溫度低于410 ℃時(shí)，流變曲線具有明顯的峰值應(yīng)力，曲線由加工硬化、動(dòng)態(tài)軟化和穩(wěn)定階段3個(gè)階段組成；當(dāng)變形溫度高于410 ℃后，峰值應(yīng)力不明顯。隨應(yīng)變量的增加，合金組織演化規(guī)律為產(chǎn)生大量無規(guī)則纏結(jié)位錯(cuò)→“多邊化”形成“位錯(cuò)墻”→分割原始晶粒成若干亞晶→亞晶合并長大并同時(shí)經(jīng)受變形→重復(fù)上述過程。應(yīng)變量的增加導(dǎo)致大量空位產(chǎn)生，刃型位錯(cuò)更易攀移、重組和對消，晶內(nèi)形成亞晶組織。求解得到合金的材料常數(shù)如下：結(jié)構(gòu)因子A為2.787×1016；變形激活能Q為217.397 kJ/mol；應(yīng)力指數(shù)n為6.11656；應(yīng)力水平參數(shù)α為0.012568 mm2/N。應(yīng)變速率和溫度對合金流變應(yīng)力的影響可以用包含Arrhenius等式的Z參數(shù)表示。
The flow behavior and microstructure evolution of Al-Li alloy were investigated by isothermal compression tests and TEM analysis. The results show that the hot plastic deformation of the alloy is heat activation process. The flow curve consists of work hardening, dynamic softening and stabilization stage, and it has obvious peak stress when the deformation temperature is below 410 ℃. Otherwise, when the deformation temperature is above 410 ℃, the peak stress is not obvious. The microstructure evolution of the test alloy experiences irregular dislocation tangles→polygonization forming dislocation walls→segmentation of the original grain into several subgrains→the coalescence and growth of subgrains undergoing deformation→repeating the above process with increasing the strains. And increasing the strain causing the increase in the number of vacancies, leading to edge dislocation easier to climb, rearrangement and annihilation and formation of subgrains in intragranular. The constants of alloy material are obtained as follows: structure factor A of 2.787×1016, deformation activation energy Q of 217.397 kJ/mol, stress exponent n of 6.11656, stress level parameter α of 0.012568 mm2/N. The effects of strain rate and temperature on the hot deformation behavior were represented by Zener-Hollomon parameter including Arrhenius term.
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