15%SiC_p/2009A1复合材料的热变形行为及加工图

Hot Deformation Behavior and Processing Map of 15%SiC_p/2009A1 Composites

为了研发高性能颗粒增强铝基复合材料,采用Gleeble-3800热模拟试验机,研究了粉末冶金15%SiC_p/2009A1复合材料在变形温度为370~520℃、应变速率为0.01~10.00 s-1条件下的高温变形特性。结果表明,当变形速率一定时,该复合材料的流变应力随变形温度升高而降低;当变形温度一定时,复合材料的流变应力随应变速率增大而提高。采用动态材料模型建立了15%SiC_p/2009A1复合材料的热加工图。热加工图表明,在较高应变速率区域(2.00~10.00 s^(-1)),出现流变失稳,有少量颗粒—基体界面开裂和SiC颗粒本身破碎。该复合材料的动态再结晶区域位于加工图的较低应变速率区域(<1.00 s^(-1)),功率耗散率值较为适中,为0.24~0.35,此时材料具有良好的塑性,适合进行热加工变形。综合加工图以及微观组织观察结果,获得了复合材料热变形的最佳工艺参数:变形温度为450~490℃、应变速率为0.01~0.10 s^(-1)。

In order to develop high performance particle reinforced aluminum matrix composites,the hot deformation characteristics of15% SiC_p/2009A1 composites fabricated by powder metallurgy route were studied by thermal compaction testing on Gleeble-3800 hotsimulation machine at temperature of 370 ～ 520 ℃ and strain rate of 0. 01 ～ 10. 00 s^-1. The results showed that the flow stress decreased with the deformation temperature increasing at a constant strain rate,and increased with the strain rate increasing at a constant temperature. The processing maps of 15% SiC_p/2009A1 composites were developed on the basis of dynamic material model. The processing maps presented unsteady zones at high strain rate（ about 2. 00 ～ 10. 00 s^-1）. There were a few separated interfaces of particlematrix and the cracked Si C particles themselves. The dynamic recrystallization region of the composite was located in the lower strain rate region（ 〈1. 00 s^-1）,where the power dissipation rate was relatively moderate,which was 0. 24 ～ 0. 35,and the material had a good plasticity which was suitable for thermal deformation. On the base of the experimental results including processing map and microstructure,the optimum hot deformation condition of the composites attained by the maps were as follows： the temperature of 450 ～ 490℃ and the strain rate of 0. 01 ～ 0. 10 s^-1.