(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； 3. 江蘇豪然噴射成形合金有限公司，鎮(zhèn)江 212009)
摘 要: 采用Gleeble-3500熱模擬試驗(yàn)機(jī)對經(jīng)過致密化的噴射成形7055鋁合金進(jìn)行熱壓縮試驗(yàn)。熱壓縮之后的樣品使用金相顯微鏡和透射電鏡觀察。結(jié)果表明：隨著熱變形溫度的升高或應(yīng)變速率的降低，峰值應(yīng)力逐漸減小。該合金的熱壓縮流變應(yīng)力行為可以用雙曲正弦形式的方程表示，也可以用Zener-Hollomon參數(shù)來描述。噴射成形7055鋁合金熱變形過程中組織演變可以使用Zener-Hollomon參數(shù)定量表征，其軟化機(jī)制主要為動態(tài)回復(fù)和動態(tài)再結(jié)晶。隨著lnZ值的降低，合金的軟化機(jī)制由動態(tài)回復(fù)逐漸轉(zhuǎn)變?yōu)閯討B(tài)再結(jié)晶且再結(jié)晶尺寸變大。變形后合金中分布的高密度、納米級的Al3Zr粒子可有效阻礙合金在熱變形中的動態(tài)再結(jié)晶。
關(guān)鍵字: 噴射成形7055鋁合金；熱變形；本構(gòu)方程；軟化機(jī)制
（1. Central South Light Alloys, Central South University, Changsha 410083, China; 2. School of Materials Science and Engineering, Central South University, Changsha 410083, China; 3. Jiangsu Haoran Spray Forming Alloys Co., Ltd., Zhengjiang 212009, China）
Abstract:The hot compression tests of spray formed 7055 aluminum alloy after densification were performed on Gleeble-3500 system in the temperature range from 340 ℃ to 450 ℃ and at strain rate range from 0.001 s-1 to 1 s-1. The sample after hot compression was observed using optical microscopy and transmission electron microscopy. The results show that the peak stress levels decrease with the increase of deformation temperature or the decrease of strain rate. The flow stress behavior of the alloy during hot compression can be represented by equation of hyperbolic sine form, which can be also described by Zener-Hollomon parameter. The microstructure evolution of spray formed 7055 aluminum alloy can be quantificationally characterized by Zener-Hollomon parameter and the main softening mechanism is dynamic recovery and dynamic recrystallization. With the decreasing of Z value, the softening mechanism of alloy gradually transformed from dynamic recovery to dynamic recrystallization and the size of recrystallized grains become larger and larger. Nano-scaled Al3Zr particles of high densities precipitating in the aluminum after deformation can effectively inhibit the dynamic recrystallization of experiment alloy.
Key words: spray formed 7055 aluminum alloy; hot deformation; constitutive equation; softening mechanism
