(1. 中南大學(xué)輕合金研究院，長沙 410083；
2. 中南大學(xué)材料科學(xué)與工程學(xué)院，長沙410083)
摘 要: 在溫度450~520 ℃和1.67×10-3~1.00×10-1 s-1初始應(yīng)變速率條件下對(duì)Al-Mg-Sc-Zr合金冷軋板材進(jìn)行拉伸實(shí)驗(yàn)，研究該合金的超塑性流變行為，探討其超塑性變形機(jī)理。結(jié)果表明：隨著變形溫度的升高，伸長率先增加后減小，在500 ℃和初始應(yīng)變速率6.67×10-3 s-1條件下獲得的最大伸長率為740%。合金的應(yīng)變速率敏感因子為0.40，激活能為101 kJ/mol；在超塑性變形過程中，合金組織發(fā)生明顯的動(dòng)態(tài)再結(jié)晶，使原始纖維狀晶粒等軸化；Al3(Sc,Zr)粒子可有效釘扎晶界，抑制晶粒長大；超塑性變形過程的主要變形機(jī)制為晶界滑移，協(xié)調(diào)機(jī)制為晶界擴(kuò)散控制的位錯(cuò)蠕變。
關(guān)鍵字: Al-Mg-Sc-Zr合金；冷軋；超塑性；變形
（1. Light Alloy Research Institute, Central South University, Changsha 410083, China;
2. School of Materials Science and Engineering, Central South University, Changsha 410083, China）
Abstract:The tensile tests for cold-rolled Al-Mg-Sc-Zr alloy were conducted at temperature of 450-500 ℃ and initial strain rate of 1.67×10-3-1.00×10-1 s-1. The flow behavior and deformation mechanism were investigated. The results show that the elongation changes as a parabola with the deformation temperature increasing, and the maximum elongation of 740% is achieved at 500 ℃ and 6.67×10-3 s-1. The strain rate sensitivity is 0.40, and the activation energy is 101 kJ/mol. The obvious dynamic recrystallization (DRX) is observed, which can transfer the grain from original fibrous structure to equiaxed microstructure. The Al3(Sc,Zr) particles pin effectively at grain boundaries to resist grain growth. The grain boundary sliding is the dominant deformation mechanism during the superplastic deformation, the dislocation creep controlled by grain boundary diffusion is the main accommodation mechanism.
Key words: Al-Mg-Sc-Zr alloy; cold-rolling; superplasticity; deformation
