Abstract The microstructures and mechanical properties of Hf compressed at the strain rates of 300 s−1、1290 s−1 and 2800 s−1 were investigated. At a strain rate of 300 s−1, dislocation slip dominated the deformation. Meanwhile, a small number of the face-centered cubic (FCC) lamellas formed via hexagonal close-packed (HCP) structure to FCC structure transformation. As the strain rate increased to 1290 s−1, both the dislocation density and the number of the FCC lamellas increased significantly. When the strain rate reached 2800 s−1, dislocation slip, phase transformation, twinning, dynamic recrystallization and shear banding occurred in the material. However, the number of the FCC lamellas decreased significantly at the strain rate of 2800 s−1, indicating that the HCP to FCC phase transformation was restrained. The temperature rise inside the specimens compressed under the strain rate of 2800 s−1 promoted deformation twinning and dynamic recrystallization. The microhardness increased gently for the specimens compressed at strain rates of 300 s−1 and 1290 s−1, while when the strain rate increased to 2800 s−1, the microhardness increased substantially. The formation of various boundary structures, including microbands, twins and FCC bands, contributes to the hardness increase by acting as obstacles to dislocation motion. In addition, the formation of new grains by dynamic recrystallization also played a role in strengthening.

中文翻译：

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纯铪高速压缩变形机理

摘要 研究了300 s-1、1290 s-1和2800 s-1应变速率下Hf的显微组织和力学性能。在 300 s-1 的应变速率下，位错滑移主导变形。同时，少量面心立方（FCC）薄片通过六方密堆积（HCP）结构向FCC结构转变而形成。随着应变速率增加到 1290 s-1，位错密度和 FCC 薄片的数量都显着增加。当应变速率达到 2800 s-1 时，材料发生位错滑移、相变、孪晶、动态再结晶和剪切带。然而，在 2800 s-1 的应变速率下，FCC 薄片的数量显着减少，表明 HCP 到 FCC 的相变受到抑制。在 2800 s-1 应变速率下压缩试样内部的温度升高促进了变形孪晶和动态再结晶。在应变速率为300 s-1和1290 s-1时压缩试样的显微硬度缓慢增加，而当应变速率增加到2800 s-1时，显微硬度显着增加。各种边界结构的形成，包括微带、孪晶和 FCC 带，通过充当位错运动的障碍来促进硬度增加。此外，动态再结晶形成的新晶粒也起到了强化作用。而当应变速率增加到 2800 s-1 时，显微硬度显着增加。各种边界结构的形成，包括微带、孪晶和 FCC 带，通过充当位错运动的障碍来促进硬度增加。此外，动态再结晶形成的新晶粒也起到了强化作用。而当应变速率增加到 2800 s-1 时，显微硬度显着增加。各种边界结构的形成，包括微带、孪晶和 FCC 带，通过充当位错运动的障碍来促进硬度的增加。此外，动态再结晶形成的新晶粒也起到了强化作用。