高纯铝在高压形变下的微结构及性能调控

MICROSTRUCTURE AND PROPERTY CONTROL OF HIGH PURITY ALUMINUM THROUGH HIGH-PRESSURE DEFORMATION

熊万能

11930068

硕士

材料工程

王培 赵予生

2021-05-21

2021-06-11

南方科技大学

深圳

铝是实际生活中使用最广泛的有色金属材料之一。与其他有色金属相比，其出色的特点让这种材料在金属中脱颖而出。例如，铝的重量比较轻，且具高强度、耐腐蚀性，能够在很多工业领域中应用，比如说在航空航天，汽车和半导体领域。但是，纯铝强度低和硬度低的缺点仅限于工业应用。传统的制造热处理工艺无法显著提高纯铝的机械性能。通过高压塑性变形过程可以细分晶粒，可以增加位错密度，并可以形成特殊的纳米结构，极大的提升纯铝的力学性能。随着铝材的使用量增加，高压技术的发展，通过高压增强铝的研究也成为当前对铝材料研究的热点。本研究以高纯铝（99.999%）为研究对象，对其在高压下进行应变处理，然后使用金相显微镜(OM)、X射线衍射分析仪(XRD)、及透射电子显微镜(TEM)等分析仪器，对高纯铝高压变形后的微观组织进行表征；通过显微硬度测试等方法，对高压高纯铝的力学性能进行探究。高压处理可以明显的细化高纯铝晶粒，随着应变的增加至80%左右，高纯铝的平均晶粒尺寸由1.25 μm下降到0.86 μm。并且当应变程度不断增加时，铝的平均晶粒尺寸呈现长大现象。随着高压纯铝应变的不断提高，纯铝的显微硬度出现先增后减的趋势，其硬度大致在高压应变为80%达到最大32 HV 左右，由高压处理可以增大纯铝的显微硬度，高压之后的试样硬度相较于原始试样，最高提升了67%，增强硬度的作用比较明显。高纯铝在高压应变后其内部分布着较多数量的位错、非稳定的晶界和位错胞等结构缺陷，这会极大的促进较大晶粒的解离。纯铝高压后沿着（111）方向进行滑移，造成宏观的塑性变形。TEM定量分析表明，相较于没有发生变形的高纯铝，位错密度由2.64×1016 m-2增加至1.54×1017 m-2，变形高纯铝的位错密度提高了约5倍。

Aluminum alloy is one of the most widely used non-ferrous metal materials in real life, and its outstanding characteristics make it stand out from the rest of the non-ferrous metals. For example, aluminum alloy is light in weight and has high strength and corrosion resistance that can be used in many industrial applications, such as aerospace, automotive, and semiconductor. However, the disadvantages of low strength and hardness of pure aluminum limites its industrial applications. The mechanical properties of pure aluminum cannot be improved by the traditional heat- treatment manufacturing process. The grain size can be subdivided by high pressure plastic deformation, the dislocation density can be increased, and the special nano-structure can be formed, which greatly improves the mechanical properties of pure aluminum. With the increasing use of aluminum and the development of high-pressure technology, the research of high-pressure reinforced aluminum has become a hot spot. In this paper, commercial pure aluminum (99.999%) is studied by means of deformation treatment under high pressure, metallographic microscope (OM) , X-ray diffraction (XRD) , transmission electron microscope, etc., and the microstructure of recovered pure aluminum samples were analyzed. The mechanical properties of high-pressure pure aluminum were investigated by means of microhardness test, and the conclusions are as follows.High-pressure treatment can refine the grain of pure aluminum , with the increase of strain to about 80% , the average grain size of pure aluminum decreased from 1.25 μm to 0.86 μm, and the grain refinement was the most at 80% strain. Afterwards the average grain size of aluminum increases with the increase of strain. With the increase of the strain of high-pressure treated pure aluminum, the microhardness increases first and then decreases. The hardness of pure aluminum reaches a maximum of 32 HV at a strain of 80%, an increase of 67% when compared to the hardness of the starting material.There are many dislocations, unstable grain boundaries and dislocation domains in high-purity aluminum after high pressure deformation, which can greatly promote the dissociation of larger grains. Pure aluminum slides along (111) direction after high pressure, resulting in macroscopic plastic deformation. The TEM quantitative analysis showed that the dislocation density increased by a factor of 7, from 2.64×1016 m-2 to 1.54×1017 m-2.

高纯铝 高压 组织 晶粒 硬度

High Purity aluminum High pressure Microstructure Grain size Hardness

中文

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南方科技大学

熊万能. 高纯铝在高压形变下的微结构及性能调控[D]. 深圳. 南方科技大学,2021.