本文選題：7085鋁合金 + 熱模擬　； 參考：《廣西大學(xué)》2017年碩士論文

【摘要】：本文以7085鋁合金為研究對象,通過添加不同量的稀土元素Y,制備RE-7085鋁合金。利用OM、SEM、TEM和XRD等手段研究了RE-7085鋁合金微觀組織變化規(guī)律及鑄態(tài)條件下的力學(xué)性能,并對實(shí)驗(yàn)結(jié)果進(jìn)行了理論上的分析和討論。采用等溫?zé)釅嚎s模擬實(shí)驗(yàn)的方法,研究了該合金在不同溫度、不同應(yīng)變速率下流變行為,建立了高溫流變模型,并確定了動(dòng)態(tài)再結(jié)晶臨界條件。主要研究成果如下:7085鋁合金微合金化結(jié)果表明:稀土元素Y能夠明顯細(xì)化7085鋁合金的鑄態(tài)組織,二次枝晶間距減小,使原來網(wǎng)狀結(jié)構(gòu)的第二相變成細(xì)條狀和魚骨狀。同時(shí),Y主要是與Al、Cu等在晶界上形成Al2Cu與Al3Y共晶化合物,沿晶界上聚集,沿枝晶分布。隨著稀土元素Y的加入,可以明顯提高7085鑄態(tài)下鋁合金的顯微硬度和室溫拉伸性能,卻對合金的導(dǎo)電性能有不利影響。RE-7085鋁合金的熱模擬實(shí)驗(yàn)結(jié)果表明:在壓縮量為50%,變形溫度為350℃-450℃,變速率為0.1s-1-5s-1條件下,合金表現(xiàn)出正的應(yīng)變速率敏感性。其真應(yīng)力-真應(yīng)變曲線在應(yīng)變速率較低而溫度較高時(shí)(ε=0.1s-1,450°C)時(shí),表現(xiàn)出明顯動(dòng)態(tài)再結(jié)晶特征;在應(yīng)變速率較高時(shí)(ε=1s-1,ε = 5s-1),表現(xiàn)出動(dòng)態(tài)回復(fù)特征。本文RE-7085鋁合金的變形激活能為175KJ/mol,根據(jù)熱變形過程中的微觀組織分析,說明稀土 Y能明顯抑制7085鋁合金在高溫變形過程中的動(dòng)態(tài)再結(jié)晶過程中晶粒的長大;合金動(dòng)態(tài)再結(jié)晶晶粒數(shù)目,隨變形溫度的升高和應(yīng)變速率的降低而有所增加,但晶粒尺寸變化不大。
[Abstract]:In this paper, 7085 aluminum alloy was studied and RE-7085 aluminum alloy was prepared by adding different amount of rare earth element Y. The changes of microstructure and mechanical properties of RE-7085 aluminum alloy under as-cast condition were studied by means of TEM and XRD. The experimental results were analyzed and discussed theoretically. The rheological behavior of the alloy at different temperature and strain rate was studied by means of isothermal compression simulation. The rheological model at high temperature was established and the critical condition of dynamic recrystallization was determined. The main results are as follows: the results of microalloying show that the rare earth element Y can refine the as-cast structure of 7085 aluminum alloy and decrease the secondary dendrite spacing, which makes the second phase of the original mesh structure become fine and fishbone. At the same time, Al2Cu and Al3Y eutectic compounds were formed at grain boundaries with Albumin and Cu, which aggregate along grain boundaries and distribute along dendrites. With the addition of rare earth element Y, the microhardness and room temperature tensile properties of 7085 as-cast aluminum alloy can be improved obviously. However, the thermal simulation results of RE-7085 aluminum alloy show that the alloy shows positive strain rate sensitivity under the conditions of 50 compression, 350 鈩，

本文編號：1976924