固溶-大变形-时效下7085铝合金的强化机理

The research of Strengthening mechanisms of 7085 aluminum alloy by solution-large-deformation

摘要:

本文的实验对象为固溶—时效和固溶—大变形(压缩、ECAP)—时效加工的7085铝合金,分别通过拉伸试验机和扫描电子显微镜(SEM)测试其拉伸性能和进行断口分析,并采用X射线衍射仪(XRD)和晶体微区取向分析技术(EBSD)对材料内部的位错密度、单元边界(小角度晶界)和晶粒边界(大角度晶界)进行表征,结合拉伸试验测得的屈服强度,定量计算强化项对大变形铝合金的强化贡献。结果表明,相比常规固溶—时效工艺,固溶—大变形—时效工艺能够显著碎化和细化晶粒,增加了单元边界的数量,促使第二相均匀分布,从而提高7085铝合金的屈服强度,并且发现强烈塑性变形加工(ECAP)的强化效果高于传统塑性变形加工(压缩变形)的效果。大变形加工也使得7085铝合金内部积累了大量位错,大变形加工对合金性能的提高主要依靠位错强化。

Abstract:

Experimental object of this paper is the solution-aging and solution-large deformation (compression,ECAP)-aging of 7085 aluminum alloy. Through the tensile testing machine and scanning electron microscope (SEM) to test the tensile properties and fracture analysis. Internal dislocation density, low angle grain boundary and high angle grain boundary of 7085 aluminum alloy under different states were characterized through X-ray diffractometer (XRD) and Electron Back Scattering Diffraction (EBSD) .Combined tensile test measured yield strength, strengthen the contribution of the large deformation strengthening aluminum items of the quantitative calculation.The results show that, compared with conventional solution-aging treatment, the solution-large deformation - aging treatment can significantly refine grain size, increase the number of low angle grain boundary, prompt uniform distribution of precipitated phase so as to advance yield stress. Especially, Equal Channel Angular Pressing (ECAP) is more effective than compression in improving overall performance. Large deformation processing of 7085 aluminum alloy also makes a lot of internal accumulation of dislocations, large deformation processing was improving performance mainly depends on the alloy dislocation strengthening and small-angle grain boundary strengthening, alloy internal solid solution strengthening and second phase strengthening has been weakened by large deformation processed.