B_(4)C_(p)/6061Al复合材料的热变形组织演变研究

Research on Microstructure Evolution of B_(4)C_(P)/6061Al Composite during Hot Deformation

为探究B_(4)C_(P)/6061Al复合材料的热变形组织演变规律,进一步优化材料的性能,课题组采用控制变量法,利用热压缩试验分别探究了在不同热变形条件(变形温度、应变速率及应变量)下B_(4)C_(P)/6061Al复合材料的微观组织特征。结果表明:变形温度越高,6061铝基体内部原子的热激活能增大,动态再结晶的形核速度提升,晶粒尺寸也不断增大;随着应变速率增大,复合材料发生动态再结晶的时间缩短,阻碍了晶粒的生长,不利于6061铝基体发生动态再结晶;应变量增加,复合材料的流变应力增大,提高了6061铝基体动态再结晶的形核效率。在不损害复合材料塑性的前提下提高强度和韧性的方法,对改善材料塑性成形能力和优化成形工艺(如轧制、锻造、挤压等)有借鉴意义。

In order to investigate the evolution law of thermal deformation microstructure of B_(4)C_(P)/6061 Al composites and further optimize the properties of the materials,the microstructure characteristics of B_(4)C_(P)/6061 Al composites under different thermal deformation conditions(deformation temperature,strain rate and strain level)were studied by using hot compression tests and control variable method.The research show that with the increase of the deformation temperature,the thermal activation energy inside the 6061 aluminum matrix materials increases,the nucleation efficiency and the grain size of the dynamic recrystallization also increases.The time for dynamic recrystallization of the composite material decreases as the strain rate increases,which restricts the growth of grains and the dynamic recrtystallization of the 6061 aluminum matrix materials.The flow stress of the composite material increases with the increase of strain,which improves the nucleation efficiency of the 6061 aluminum matrix materials dynamic recrystallization.The method that enhances strength and toughness of the composites without damages of the plasticity has important reference significance for improving the plastic forming ability of materials and optimizing the forming process(such as rolling,forging,extrusion,etc.).