(1. 中南大学 轻合金研究院，长沙 410083； 2. 中南大学 材料科学与工程学院，长沙 410083； 3. 江苏豪然喷射成形合金有限公司，镇江 212009)
摘 要: 采用Gleeble-3500热模拟试验机对经过致密化的喷射成形7055铝合金进行热压缩试验。热压缩之后的样品使用金相显微镜和透射电镜观察。结果表明：随着热变形温度的升高或应变速率的降低，峰值应力逐渐减小。该合金的热压缩流变应力行为可以用双曲正弦形式的方程表示，也可以用Zener-Hollomon参数来描述。喷射成形7055铝合金热变形过程中组织演变可以使用Zener-Hollomon参数定量表征，其软化机制主要为动态回复和动态再结晶。随着lnZ值的降低，合金的软化机制由动态回复逐渐转变为动态再结晶且再结晶尺寸变大。变形后合金中分布的高密度、纳米级的Al3Zr粒子可有效阻碍合金在热变形中的动态再结晶。
关键字: 喷射成形7055铝合金；热变形；本构方程；软化机制
（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
