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采用真空热压烧结法制备了纳米Al2O3弥散强化铜为基体,W颗粒为增强相的W(50)/Cu-Al2O3新型复合材料。在Gleeble-1500D热模拟机上对真空热压烧结W(50)/Cu-Al2 O3复合材料进行等温热压缩实验,研究了在变形温度为650～950℃;变形速率为0.01～5 s-1;最大真应变为0.7条件下的流变应力行为。结果表明:在实验条件下,复合材料W(50)/Cu-Al2O3存在明显的动态再结晶特征,即变形初期,流变应力随着应变量的增大而迅速增大,达到峰值之后流变应力逐渐趋于平稳,不随应变的增加而明显变化。变形温度和变形速率对流变应力影响显著,随着温度的升高和应变速率的减小,峰值应力逐渐减小,并且在晶界交叉处出现再结晶晶粒,并逐渐增多。复合材料的主要软化机制为动态再结晶。建立了复合材料高温变形时的流变应力本构方程,并确定了热变形激活能Q为176.05 kJ/mol。
A novel W (50) / Cu-Al2O3 composite with W particles as reinforcing phase was prepared by vacuum hot-pressing sintering. The isothermal hot compression experiments of vacuum hot-pressed sintered W (50) / Cu-Al 2 O 3 composites were carried out on a Gleeble-1500D thermal simulator. The effects of deformation temperature at 650-950 ℃ and deformation rate of 0.01-5 s -1 ; The maximum true strain of 0.7 flow stress behavior. The results show that the dynamic recrystallization of W (50) / Cu-Al2O3 composites shows obvious dynamic recrystallization under the experimental conditions. That is to say, the rheological stress rapidly increases with the increase of strain at the initial stage of deformation. The stress gradually tends to be stable and does not change significantly with the increase of strain. Deformation temperature and deformation rate have a significant influence on the flow stress. With the increase of temperature and strain rate, the peak stress decreases gradually, and the recrystallized grains appear at the intersection of the grain boundaries and gradually increase. The main softening mechanism of composites is dynamic recrystallization. The rheological stress constitutive equation of the composites was established and the heat activation energy Q was 176.05 kJ / mol.