Al-0.2Sc-0.04Zr超耐热变形铝合金高温流变行为

High temperature flow behaviors of wrought Al-0.2Sc-0.04Zr aluminium alloy

在应变速率为0.001~5 s^(-1)、变形温度为440~600℃条件下,在Geeble-1500D热模拟试验机上对Al-0.2Sc-0.04Zr(质量分数/%)变形铝合金开展单向热压缩试验,研究其高温流变行为。结果表明:流变应力随变形温度的减小和应变速率的增加而增大,应力曲线经历线性-硬化阶段、抛物线-动态回复阶段、完全动态再结晶-稳态变形阶段;压缩变形后试样中间部位的组织呈条带状,晶粒沿垂直于压缩方向被压扁和拉长,再结晶晶粒尺寸随变形温度的升高和应变速率的减小而增大;建立的Z参数-Arrhenius型本构方程对Al-0.2Sc-0.04Zr合金峰值应力的预测平均相对误差率仅为7.428%;该合金较高的热变形激活能(642.575 kJ/mol)和应变指数(13.810 5)与第二相粒子Al3(Sc,Zr)有关。

In order to study the high temperature flow behavior of wrought Al-0.2Sc-0.04Zr（mass fraction/%）aluminium alloy,the hot compression deformation was tested at the temperatures from 440 ℃ to 600 ℃ and strain rates from 0.001 s^（-1） to 5 s^（-1） on Gleeble-1500D thermo-simulation machine.The experiments show that the flow stress increases with the decrease of deformation temperature and the increase of strain rate.The flow stress obtained from experiments consists of three different stages：linear work-hardening stage,parabolic curve-dynamic recovery stage,completely dynamic recrystallization-steady stage.The microstructure of the middle part of the specimens after compression deformation exhibits a banding distribution with flaser and elongated grains in the vertical direction of compression.The recrystallized grain size increases with the decrease of strain rate and the increase of deformation temperature.The Arrhenius-type constitutive equation containing the Z parameter was established and the relative error rate is only 7.428%.The alloy has high deformation activation energy and stress exponent,which are related to the second phase dispersed particles Al_3（Sc,Zr）.