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。
The newly developed W（50）/Cu-Al2O3 composites were prepared with the matrix of copper dispersion-strengthened by Al2O3 particles and the reinforced phase of tungsten particles by vacuum hot-press sintering method.With the test temperature varying from 750 ℃ to 950 ℃,the strain rate ranging from 0.1 s-1to 5 s-1 and the true strain of 0.7,the isothermal compression test of the W（50）/Cu-Al2O3 composites were carried out on a Gleeble-1500D thermal simulator.The results indicate that the W（50）/Cu-Al2O3 composite shows the dynamic recrystallization characteristics under the test condition.Both the deformation temperature and the strain rate have obvious influence on flow stress.The flow stress increases with increasing strain and tends to be constant after the peak value.The peak stress value increases with increasing strain rate and decreases with increasing deformation temperature.With increasing the temperature and decreasing strain rate,more and more strain-free recrystallized fine grains at intersections of grain boundary are observed.It indicates that the main softening mechanism of the composites during hot compression deformation is dynamic recrystallization.The hot compression deformation behavior can be represented by a Zener-Hollomon parameter in the hyperbolic constitutive equations.The average hot deformation activation energy of the composites is calculated,which is 176.05 kJ/mol.
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