基于各向异性特征的7050-T7451铝合金位错密度及其演变规律

Dislocation Density and Its Evolution of Aluminum Alloy 7050 Based on Anisotropy

7050-T7451铝合金被广泛用于制造具有轻量化、薄壁化需求的航空航天结构件。作为多晶体金属材料,铝合金塑性变形行为呈现出明显的各向异性特征,不同的加载路径直接影响薄壁扁宽件的服役性能,因此考虑各向异性特征深入分析材料力学性能的微观响应机制具有重要的工程意义。以7050-T7451铝合金为研究对象,结合试验与X射线衍射线形分析方法,采用位错密度值定量表征并研究位错在不同空间角度取向、不同加载条件下的演化规律。结果表明:晶粒取向随着变形过程而发生变化,且具有(111)晶面择尤取向现象;不同加载条件、成形角度下位错密度取值范围介于0.275 2×10;~1.581 8×10;m;不同成形角度下的位错密度随应变率的提高均先增大后减小,随温度的变化则具有明显差异;不同加载条件下,位错密度在成形角度0°~90°范围内均呈现出先减小后增大再减小后增大的趋势,室温下成形角度为45°时,位错密度达到最大值1.581 8×10;m;。7050-T7451铝合金微观变形机制的研究为掌握材料各向异性变形行为及其在航空航天领域的工程应用提供了理论支撑。

7050-T7451 aluminum alloy is widely used in aerospace structures, which have the requirements of lightweight and thin wall. As a polycrystalline metal material, the plastic deformation behavior of aluminum alloy presents obvious anisotropy characteristics. Different loading paths will seriously affect the service performance of thin-walled flat-wide parts. Therefore, it is of great significance to deeply analyze the microscopic response mechanism of anisotropy of material mechanical properties. Taking 7050-T7451 aluminum alloy as the research object, combining experiments and X-ray diffraction line analysis methods, the dislocation density value is used to quantitatively characterize and study the movement of dislocations under different spatial angle orientations and different loading conditions. The results show that the grain orientation changes with the deformation process, and there is a phenomenon of(111) crystal plane selective orientation. The range of dislocation density under different loading conditions and forming angles is between 0.275 2×10;-1.581 8×10;m;. The dislocation density at different forming angles increases first and then decreases with the increase of strain rate, and there is a significant difference with temperature changes. Under different loading conditions, the dislocation density in the forming angle range of 0°-90°shows a trend of first decreasing, then increasing,then decreasing and increasing. When the forming angle is 45°at room temperature, the dislocation density reaches the maximum of 1.581 8×10;m;. The research on the micro-deformation mechanism of 7050-T7451 aluminum alloy can better grasp the anisotropic deformation behavior of the material and provide theoretical support for its engineering application in the aerospace field.