论文部分内容阅读
研究锆合金在应变速率1000s-1动态压缩条件下的显微组织演化规律。基于相同应变速率下多次撞击的方法实现锆合金动态压缩下4个不同的应变水平。在不同的应变水平下,应力—应变曲线具有明显的应变硬化效应,几乎观察不到明显的热软化效应。标定的晶粒边界图像表明,在不同的应变水平下,在变形组织内均可观察到大量的小角晶界,同时,小角晶界的数量和密度随着应变的增加而增多。除了在晶粒边界图像中观察到的小角晶界和大角晶界外,在不同的应变水平下还可观察到孪晶界。孪晶界的类型主要包括{10 1 2}、{11 2 1}拉伸孪晶和{11 2 2}压缩孪晶,且大多数孪晶界为{10 1 2}拉伸孪晶。随着应变水平的增加,变形组织中孪晶界的密度变化不明显。基于不同应变水平下变形组织的表征,提出了动态载荷下锆合金变形和演化过程。显微硬度测试表明,撞击试样的硬度随着应变的增加而逐渐增大,这主要与位错塞积引起的应变硬化有关。
The microstructure evolution of zirconium alloy at dynamic strain rate of 1000s-1 was studied. Four different strain levels were achieved under dynamic compression of zirconium alloys based on multiple impacts at the same strain rate. At different strain levels, the stress-strain curve has a significant strain-hardening effect with almost no apparent thermal softening effect observed. The calibrated grain boundary images show that a large number of small-angle grain boundaries can be observed in the deformed tissue at different strain levels. Meanwhile, the number and density of small-angle grain boundaries increase with the increase of strain. In addition to the small-angle grain boundaries and the large-angle grain boundaries observed in grain boundary images, twin boundaries can also be observed at different strain levels. The types of twin boundaries mainly include {10 1 2}, {11 2 1} stretched twins and {11 2 2} compressed twins, and most of the twin boundaries are {10 1 2} stretched twins. With the increase of the strain level, the density of the twins in the deformed tissue did not change obviously. Based on the characterization of the deformed structure at different strain levels, the deformation and evolution of the zirconium alloy under dynamic loading were proposed. The microhardness tests show that the hardness of the impact specimen increases with the increase of strain, which is mainly related to the strain hardening caused by the dislocation plugging.