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为研究低温下动态冲击对2519A铝合金流变应力和组织演化的影响,在低温下利用霍普金森压杆对2519A-T87态铝合金进行应变速率为1000~4200 s-1的动态冲击压缩实验,同时运用光学显微镜与透射电镜,对低温下的冲击微观组织进行观察和分析。结果表明:在低温环境下,绝热剪切带中心区域为亚晶组织,再结晶程度较低;同时,在形变带内出现长度较短、连续性较差的微裂纹,裂纹末端向基体扩展。随着冲击温度的降低,材料的屈服抗力迅速增加,出现绝热剪切带的临界应变速率随之降低。在中高应变速率下,长条状弥散相粒子发生不同程度的脆性断裂,从而引起流变应力的迅速提高。
In order to study the influence of dynamic impact on the flow stress and microstructure evolution of 2519A aluminum alloy at low temperature, dynamic shock compression test of 2519A-T87 aluminum alloy at strain rate of 1000-4200 s-1 was carried out at low temperature using Hopkinson pressure bar At the same time, the microstructure of the impact at low temperature was observed and analyzed by optical microscope and transmission electron microscope. The results show that in the low temperature environment, the central region of the adiabatic shear zone is subgrain, and the degree of recrystallization is low. At the same time, the microcracks with shorter length and poorer continuity appear in the deformation zone, and the crack tip expands to the matrix. As the impact temperature decreases, the yield resistance of the material increases rapidly, and the critical strain rate of adiabatic shear band decreases. At medium and high strain rates, brittle fracture of the elongated dispersoid phase occurs to varying extents, causing a rapid increase in flow stress.