纳米晶Cu的制备与力学性能的研究
发布时间：2019-04-23 17:03
【摘要】：近几年来，我们发现了大量关于纳米晶金属力学性能的研究。纳米晶金属的力学性能表征和测试手段也是层出不穷。随着纳米晶金属制备技术的不断进步，材料的晶粒尺寸、结构和纯度都可以实现精密控制和不断优化，这就为纳米晶金属力学性质的研究与发展提供了很好的技术支持，基于这一背景，我们通过实验合成不同晶粒尺寸范围和结构的纳米晶Cu并对其力学性质进行研究，从而进一步分析纳米晶金属在不同条件下的变形机理，最终为纳米晶金属的应用提供理论支撑。为了达到上述目标，我们的具体工作如下： 1.不同晶粒尺寸的纳米晶Cu分别由磁控溅射和电刷镀技术制备。我们利用实验材料，设备，并进行了实验参数的优化，从而实现了纳米晶Cu晶粒尺寸的控制。对于电刷镀制备纳米晶Cu，通过控制电流密度和Cu离子的浓度，可以控制晶粒尺寸的范围非常广，，制备出了不同晶粒尺寸的纳米晶Cu试样，并可以控制孪晶的生长。对于磁控溅射制备纳米晶Cu，通过改变溅射功率，溅射气压，可以把晶粒控制在更小的范围内。不同纳米材料的微观结构和晶粒尺寸是通过透射电子显微镜进行观察的。 2.我们将用电刷镀制备好的~59nm，~120nm和~200nm的纳米晶Cu进行拉伸试验，通过对不同拉伸速率下的应力应变曲线的分析，我们可以知道纳米晶Cu的弹性，塑性与应变速率与晶粒尺寸的关系，通过对拉伸后形貌与断口形貌的分析可知：纳米晶Cu的断口有明显的韧窝形貌，为塑性断裂。韧窝的形貌与断裂的方式与晶粒尺寸与应变速率有着紧密的联系。 3.我们对晶粒尺寸从~22nm到~210nm的纳米晶Cu进行深度敏感纳米压痕实验，利用Berkovich压头并将应变速率控制在0.004s-1，0.04s-1和0.4s-1。我们利用激光共聚焦显微镜观察压痕后的形貌并测量变形后的深度变化。我们建立了三个实验参数(hb，hi和hd)来表征在应变速率和晶粒尺寸影响下的变形程度。从而探究应变速率和晶粒尺寸和压痕后形貌之间的关系。为纳米压痕计算材料的硬度与弹性模量提供理论指导。 4.我们对~10nm和~23nm Cu利用纳米压痕仪进行蠕变测试。应变速率控制从4×10-1s-1变到4×10-3s-1。通过分析我们知道：小晶粒尺寸试样在高应变速率下蠕变应变速率要大。是由于在这种条件下，加载阶段会存储大量的位错，从而影响保载阶段的蠕变行为。另外，通过将实验所得蠕变应变速率和理论蠕变应变速率进行比较，可以看出~10nm Cu所存储的位错将会很快被吸收，从而使得晶界滑移和Coble蠕变控制蠕变过程。对于~23nm Cu，蠕变过程则是由起初的位错运动和之后的晶界滑移所主导。
[Abstract]:In recent years, we have found a lot of research on the mechanical properties of nanocrystalline metals. The mechanical properties and testing methods of nanocrystalline metals are also emerging in endlessly. With the development of the preparation technology of nanocrystalline metals, the grain size, structure and purity of the materials can be controlled and optimized, which provides a good technical support for the research and development of the mechanical properties of nanocrystalline metals. Based on this background, we synthesized nanocrystalline Cu with different grain sizes and structures by experiments and studied its mechanical properties, so as to further analyze the deformation mechanism of nanocrystalline metals under different conditions. Finally, it provides theoretical support for the application of nanocrystalline metals. In order to achieve the above-mentioned objectives, our specific work is as follows: 1. Nanocrystalline Cu with different grain sizes were prepared by magnetron sputtering and brush plating. In order to control the grain size of nanocrystalline Cu, the experimental materials and equipment are used to optimize the experimental parameters. By controlling the current density and the concentration of Cu ions, nanocrystalline Cu, samples with different grain sizes were prepared by controlling the current density and the concentration of Cu ions, and the growth of twins was also controlled. Nanocrystalline Cu, prepared by magnetron sputtering can be controlled in a smaller range by changing sputtering power and sputtering pressure. The microstructure and grain size of different nano-materials are observed by transmission electron microscope (TEM). 2. The nano-crystalline Cu of ~ 59 nm, 120 nm and ~ 200nm prepared by brush plating has been tested by tensile test. By analyzing the stress-strain curves at different tensile rates, we can know the elasticity of nanocrystalline Cu. The relationship between plasticity and strain rate and grain size. Through the analysis of tensile morphology and fracture morphology, it can be seen that the fracture surface of nanocrystalline Cu has obvious dimple morphology, which is plastic fracture. The morphology and fracture mode of dimples are closely related to grain size and strain rate. 3. The depth sensitive nano indentation experiment of nanocrystalline Cu with grain size from ~ 22nm to ~ 210nm was carried out. The strain rate was controlled at 0.004s / 1, 0.04s / 1 and 0.4s / 1.by using the Berkovich indenter and the strain rate was controlled at 0.004s / 1, 0.04s / 1 and 0.4s / 1 respectively. We use laser confocal microscope to observe the morphology of indentation and measure the depth change after deformation. Three experimental parameters (hb,hi and hd) were established to characterize the deformation degree under the influence of strain rate and grain size. The relationship between strain rate, grain size and indentation morphology was investigated. It provides theoretical guidance for calculating hardness and elastic modulus of nano-indentation materials. 4. We tested the creep of ~ 10nm and ~ 23nm Cu by nano indentation apparatus. Strain rate control from 4 脳 10-1s-1 to 4 脳 10-3 sv. Through the analysis, we know that the creep strain rate of small grain size specimen is larger at high strain rate. The reason is that under this condition, a large number of dislocations will be stored in the loading phase, which will affect the creep behavior of the loading phase. In addition, by comparing the experimental creep strain rate with the theoretical creep strain rate, it can be seen that the dislocation stored by ~ 10nm Cu will be absorbed quickly, which makes grain boundary slip and Coble creep control the creep process. The creep process of ~ 23nm Cu, is dominated by the initial dislocation motion and the subsequent grain boundary slip.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.1;O614.121
本文编号：2463638
[Abstract]:In recent years, we have found a lot of research on the mechanical properties of nanocrystalline metals. The mechanical properties and testing methods of nanocrystalline metals are also emerging in endlessly. With the development of the preparation technology of nanocrystalline metals, the grain size, structure and purity of the materials can be controlled and optimized, which provides a good technical support for the research and development of the mechanical properties of nanocrystalline metals. Based on this background, we synthesized nanocrystalline Cu with different grain sizes and structures by experiments and studied its mechanical properties, so as to further analyze the deformation mechanism of nanocrystalline metals under different conditions. Finally, it provides theoretical support for the application of nanocrystalline metals. In order to achieve the above-mentioned objectives, our specific work is as follows: 1. Nanocrystalline Cu with different grain sizes were prepared by magnetron sputtering and brush plating. In order to control the grain size of nanocrystalline Cu, the experimental materials and equipment are used to optimize the experimental parameters. By controlling the current density and the concentration of Cu ions, nanocrystalline Cu, samples with different grain sizes were prepared by controlling the current density and the concentration of Cu ions, and the growth of twins was also controlled. Nanocrystalline Cu, prepared by magnetron sputtering can be controlled in a smaller range by changing sputtering power and sputtering pressure. The microstructure and grain size of different nano-materials are observed by transmission electron microscope (TEM). 2. The nano-crystalline Cu of ~ 59 nm, 120 nm and ~ 200nm prepared by brush plating has been tested by tensile test. By analyzing the stress-strain curves at different tensile rates, we can know the elasticity of nanocrystalline Cu. The relationship between plasticity and strain rate and grain size. Through the analysis of tensile morphology and fracture morphology, it can be seen that the fracture surface of nanocrystalline Cu has obvious dimple morphology, which is plastic fracture. The morphology and fracture mode of dimples are closely related to grain size and strain rate. 3. The depth sensitive nano indentation experiment of nanocrystalline Cu with grain size from ~ 22nm to ~ 210nm was carried out. The strain rate was controlled at 0.004s / 1, 0.04s / 1 and 0.4s / 1.by using the Berkovich indenter and the strain rate was controlled at 0.004s / 1, 0.04s / 1 and 0.4s / 1 respectively. We use laser confocal microscope to observe the morphology of indentation and measure the depth change after deformation. Three experimental parameters (hb,hi and hd) were established to characterize the deformation degree under the influence of strain rate and grain size. The relationship between strain rate, grain size and indentation morphology was investigated. It provides theoretical guidance for calculating hardness and elastic modulus of nano-indentation materials. 4. We tested the creep of ~ 10nm and ~ 23nm Cu by nano indentation apparatus. Strain rate control from 4 脳 10-1s-1 to 4 脳 10-3 sv. Through the analysis, we know that the creep strain rate of small grain size specimen is larger at high strain rate. The reason is that under this condition, a large number of dislocations will be stored in the loading phase, which will affect the creep behavior of the loading phase. In addition, by comparing the experimental creep strain rate with the theoretical creep strain rate, it can be seen that the dislocation stored by ~ 10nm Cu will be absorbed quickly, which makes grain boundary slip and Coble creep control the creep process. The creep process of ~ 23nm Cu, is dominated by the initial dislocation motion and the subsequent grain boundary slip.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.1;O614.121
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