NiP纳米非晶合金的微纳米力学性能研究

发布时间：2018-02-10 07:11

本文关键词： 纳米非晶甩带非晶 SAXS 纳米压痕仪纳微米力学性能　出处：《南京理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：本文通过脉冲电化学沉积以及甩带法分别制备NiP纳米非晶合金以及对应成份的NiP非晶合金,通过X射线衍射分析(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)以及小角度X射线散射(SAXS)等结构表征研究电沉积纳米非晶合金与熔淬甩带非晶合金之间的结构差异,发现脉冲电沉积样品由纳米级别的颗粒物堆垛而成,颗粒与颗粒间存在非晶态的界面。微纳米力学性能方面,首先使用纳米压痕仪的Berkovich三角锥压头对纳米非晶与甩带非晶进行恒载荷模式下的杨氏模量和硬度测试。在弹性模量方面两者差距不明显,但是在硬度方面,甩带非晶比纳米非晶高百分之十六。随后通过聚焦离子束FIB加工500 nm到2 μm的纳微米级圆柱,采用纳米压痕仪器的金刚石平压头进行压缩实验,相对甩带非晶在变形过程中呈现的脆性断裂,电沉积纳米非晶压缩实验中产生了均匀塑性变形,其蘑菇状的均匀塑性变形方式揭示了纳米非晶特殊的变形机理。纳米非晶颗粒之间的界面作为剪切带的优先形核点,形核后形成相互缠结的剪切带,这种缠结的剪切带之间相互影响并且吸收变形能,形成了网状的多剪切带能够防止单一剪切带的快速扩展而引发的失效。此外对不同尺寸的纳米非晶圆柱进行压缩实验后发现,在500 nm～2μm范围内,尺寸越大塑性变形更加均匀而且变形更加稳定,这可能是纳米非晶不同于传统非晶"小尺寸效应"的一种独特的力学性能。通过纳米非晶300 nm试样的TEM下原位拉伸的研究,发现纳米非晶在保持高强度高硬度的同时,发生了非晶中极其罕见颈缩现象,断裂前10.67%的应变变形量极大地化解了传统非晶最致命的应用缺点:脆性断裂,这极大程度上提高非晶材料的塑性性能。这种力学性能的纳米非晶存在着广阔的应用前景,尤其是在微机电系统(MEMS)方面,有着重大的指导意义。
[Abstract]:In this paper, NiP nanocrystalline alloy and NiP amorphous alloy with corresponding composition were prepared by pulsed electrochemical deposition and band throwing method, respectively. The structural differences between electrodeposited nanocrystalline alloys and melt-quenched amorphous alloys were studied by means of X-ray diffraction analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS). It was found that the samples were stacked by nano-particles, and there was an amorphous interface between the particles and the particles. First, the Young's modulus and hardness of nanocrystalline and ribbon amorphous were tested under constant load mode by using the Berkovich triangular cone indenter of nano-indentation instrument. The difference in elastic modulus was not obvious, but the hardness was not obvious. The amorphous ribbon is 16% higher than the nanocrystalline. Then the nanometer-sized cylinder with 500nm to 2 渭 m is fabricated by focused ion beam FIB, and the compression experiment is carried out by using the diamond flat indenter with nano-indentation instrument. Compared with the brittle fracture in the deformation process, the uniform plastic deformation occurs in the compression experiment of nanocrystalline electrodeposition. The mushroom shaped uniform plastic deformation mode reveals the special deformation mechanism of nanocrystalline. The interface between nanocrystalline particles serves as the preferred nucleation point of shear band and forms a tangled shear band after nucleation. The tangled shear bands interact with each other and absorb the deformation energy, forming a network of multi-shear bands that can prevent the failure caused by the rapid expansion of a single shear band. In addition, the compression experiments of nanocrystalline cylinders of different sizes show that, In the range of 500 nm~2 渭 m, the larger the size, the more uniform the plastic deformation is and the more stable the deformation is. This may be a unique mechanical property of nanocrystalline, which is different from the traditional amorphous "small size effect". Through the study of in-situ tensile of nanocrystalline 300nm sample under TEM, it is found that nanocrystalline keeps high strength and high hardness while maintaining high strength and high hardness. A very rare necking phenomenon occurred in amorphous, and the strain deformation of 10.67% before fracture greatly resolved the most fatal application disadvantage of traditional amorphous: brittle fracture. This greatly improves the plastic properties of amorphous materials. This kind of mechanical properties of nanocrystalline amorphous has a broad application prospect, especially in MEMS / MEMS, which has great guiding significance.
【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG139.8;TB383.1

【参考文献】