發(fā)布時(shí)間：2018-02-10 07:11

  本文關(guān)鍵詞： 納米非晶 甩帶非晶 SAXS 納米壓痕儀 納微米力學(xué)性能　出處：《南京理工大學(xué)》2017年碩士論文　論文類(lèi)型：學(xué)位論文

【摘要】：本文通過(guò)脈沖電化學(xué)沉積以及甩帶法分別制備N(xiāo)iP納米非晶合金以及對(duì)應(yīng)成份的NiP非晶合金,通過(guò)X射線衍射分析(XRD)、掃描電子顯微鏡(SEM)、透射電子顯微鏡(TEM)以及小角度X射線散射(SAXS)等結(jié)構(gòu)表征研究電沉積納米非晶合金與熔淬甩帶非晶合金之間的結(jié)構(gòu)差異,發(fā)現(xiàn)脈沖電沉積樣品由納米級(jí)別的顆粒物堆垛而成,顆粒與顆粒間存在非晶態(tài)的界面。微納米力學(xué)性能方面,首先使用納米壓痕儀的Berkovich三角錐壓頭對(duì)納米非晶與甩帶非晶進(jìn)行恒載荷模式下的楊氏模量和硬度測(cè)試。在彈性模量方面兩者差距不明顯,但是在硬度方面,甩帶非晶比納米非晶高百分之十六。隨后通過(guò)聚焦離子束FIB加工500 nm到2 μm的納微米級(jí)圓柱,采用納米壓痕儀器的金剛石平壓頭進(jìn)行壓縮實(shí)驗(yàn),相對(duì)甩帶非晶在變形過(guò)程中呈現(xiàn)的脆性斷裂,電沉積納米非晶壓縮實(shí)驗(yàn)中產(chǎn)生了均勻塑性變形,其蘑菇狀的均勻塑性變形方式揭示了納米非晶特殊的變形機(jī)理。納米非晶顆粒之間的界面作為剪切帶的優(yōu)先形核點(diǎn),形核后形成相互纏結(jié)的剪切帶,這種纏結(jié)的剪切帶之間相互影響并且吸收變形能,形成了網(wǎng)狀的多剪切帶能夠防止單一剪切帶的快速擴(kuò)展而引發(fā)的失效。此外對(duì)不同尺寸的納米非晶圓柱進(jìn)行壓縮實(shí)驗(yàn)后發(fā)現(xiàn),在500 nm～2μm范圍內(nèi),尺寸越大塑性變形更加均勻而且變形更加穩(wěn)定,這可能是納米非晶不同于傳統(tǒng)非晶"小尺寸效應(yīng)"的一種獨(dú)特的力學(xué)性能。通過(guò)納米非晶300 nm試樣的TEM下原位拉伸的研究,發(fā)現(xiàn)納米非晶在保持高強(qiáng)度高硬度的同時(shí),發(fā)生了非晶中極其罕見(jiàn)頸縮現(xiàn)象,斷裂前10.67%的應(yīng)變變形量極大地化解了傳統(tǒng)非晶最致命的應(yīng)用缺點(diǎn):脆性斷裂,這極大程度上提高非晶材料的塑性性能。這種力學(xué)性能的納米非晶存在著廣闊的應(yīng)用前景,尤其是在微機(jī)電系統(tǒng)(MEMS)方面,有著重大的指導(dǎo)意義。
[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.
【學(xué)位授予單位】：南京理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：TG139.8;TB383.1

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相關(guān)期刊論文 前1條

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本文編號(hào)：1499954