高压对金属玻璃性能的影响和金属玻璃β弛豫行为研究

发布时间：2018-02-10 13:44

本文关键词： 金属玻璃 β弛豫高压稳定性玻色峰热膨胀　出处：《中国科学院大学(中国科学院物理研究所)》2017年博士论文　论文类型：学位论文

【摘要】：弛豫一直是非晶态材料的基本问题,也一直是非晶材料研究的热点方向。本文首先研究了金属玻璃的β弛豫行为。不同于大多数金属玻璃体系,我们制备出的LaGa基三元金属玻璃具有明显的β弛豫峰。我们用镓元素分别替代镧、钴和镍这三种元素,都发现随着镓元素含量的增加,β弛豫峰越来越明显。通过应力弛豫方法,研究了镓含量不同的金属玻璃的应力弛豫行为,得出了它们的非均匀性和流变单元的的演变规律。由于镓元素的熔点非常低,在近室温镓原子可以被看出是类液体原子,是金属玻璃的流变单元主要组成。通过流变单元模型很好的解释了镓元素对金属玻璃的β弛豫行为的影响。具有明显β弛豫峰的LaGa基金属玻璃可以作为模型体系研究金属玻璃的弛豫和塑性机理。高压是调节材料结构和性能有效的手段。在Pd40.16Ni9.64Cu30.12P20.08金属玻璃中,通过室温高压的方法制备出了超稳定大块金属玻璃。超稳定金属玻璃具有更高的玻璃转变温度和晶化温度,表现出更高的动力学稳定性。超稳定金属玻璃同时还具有更高的密度和硬度。即使将超稳定玻璃进行升温至过冷液相区处理,它依然保持着原来的稳定性,说明它具有很高的热稳定性。通过调节压力,研究了金属玻璃的稳定性、硬度和密度的演变规律,发现它们都随压力单调增加。这一结果说明高压是制备高稳定性和性能的大块金属玻璃非常独特和有效的手段,可以推动金属玻璃的设计和理解金属玻璃基本问题。玻色峰一直是非晶材料重要的低温物性。我们研究了高压和退火对典型金属玻璃的玻色峰和热膨胀的影响。在退火过程中,我们发现玻色峰强度和线性热膨胀系数表现出单调衰减行为,而在高压下,玻色峰强度和线性热膨胀系数都先减小后增加。在高压下和退火过程中,玻色峰强度和线性热膨胀系数都表现出了明确的线性关系。这种线性关系说明了玻色峰与非简谐振动有直接的关联,并提供了清晰的图像深入地理解玻色峰的本质。为了探索具有室温和高温的零膨胀和负膨胀材料。我们研究了压力对材料热膨胀性能的影响。先通过室温高压方法调节了金属玻璃的微观结构,后将金属玻璃进行晶化处理,我们制备出了正膨胀、近零膨胀和负膨胀材料。通过调节压力,Pd40.16Ni9.64Cu30.12P20.08晶体材料的热膨胀系数可以在1.49×10-5/K到-2.93×10-5/K范围内可控的调节,可以实现零膨胀。近零膨胀和负膨胀材料在室温到553 K温区内的平均线性膨胀系数分别是0.67×10-5/K和-2.39×10-5/K。晶体的线性热膨胀系数随着压力的升高而逐渐减小,是由于压力使得金属玻璃的流变单元减少,微观结构非均匀性减弱,从而使得晶体材料中富Cu而无Pd的析出晶体相Ⅰ逐渐较少,而含有Pd和Cu元素的基底晶体相Ⅱ逐渐增多。这一结果说明高压是制备室温和高温零膨胀和负膨胀材料非常独特和有效的手段,可以推动材料的设计和应用,和帮助理解金属玻璃和零负膨胀材料的基本问题。
[Abstract]:Relaxation has been the basic problem of non crystalline material, it has been a hot research direction of amorphous materials. This paper studies the beta relaxation behavior of metallic glass. Unlike most metallic glass system, we made three yuan of LaGa based metallic glass prepared has obvious beta relaxation peak. We replace LA with gallium, cobalt and nickel are found in these three elements, with the increase of gallium content, beta relaxation peak is more and more obvious. By the stress relaxation method of metallic glass gallium content different stress relaxation behavior, obtains their heterogeneity and the evolution of flow unit the melting point of gallium. Because the law is very low, in the past can be seen at room temperature gallium atoms liquid atoms, is primarily composed of rheological unit of metallic glass. The flow unit model can well explain the beta relaxation of gallium on metal glass relaxation behaviors. Ring. LaGa based metallic glass has obvious beta relaxation peak can be used as a model system to study the metal relaxation of glass and plastic. The mechanism of hypertension is adjusting the structure and performance of materials effectively. In Pd40.16Ni9.64Cu30.12P20.08 metallic glass, by high pressure method at room temperature to produce ultra stable bulk metallic glass ultra stable metal glass. Has a higher glass transition temperature and crystallization temperature, dynamics showed higher stability. The super stable metallic glass also has higher density and hardness. Even the ultra stable glass heating to the supercooled liquid region, it still maintains the original stability, it has high thermal stability. By adjusting the pressure, stability of metallic glass, evolution of hardness and density, which increased monotonically with pressure. The results show that high pressure is the preparation of high stability Bulk metallic glass and the performance is very unique and effective means, can promote the metallic glass design and understanding of metallic glass basic problem. The boson peak has been the Cryogenic Properties of amorphous materials. We studied the effects of high pressure and annealing on the typical metallic glass boson peak and thermal expansion in the annealing process., we found that the boson peak intensity and linear thermal expansion coefficient showed a monotonic decay behavior, and under high pressure, the boson peak intensity and linear thermal expansion coefficient decreased and then increased. Under high pressure and annealing process, the boson peak intensity and linear thermal expansion coefficient showed a clear linear relationship this linear relationship. The boson peak is directly associated with anharmonic vibration, nature and provides a clear understanding of the image of the boson peak. In order to explore with zero expansion at room temperature and high temperature and negative expansion materials. We studied the effect of pressure on the thermal. The microstructure of metallic glass by adjusting to room temperature high pressure method, after the metal glass crystallization treatment, we prepared is expanding, near zero thermal expansion and negative thermal expansion materials. By adjusting the pressure, the thermal expansion coefficient of Pd40.16Ni9.64Cu30.12P20.08 crystals can adjust -2.93 * 10-5/K range at 1.49 * 10-5/K, can achieve zero expansion. Near zero thermal expansion and negative expansion materials at room temperature to 553 K temperature range the average linear expansion coefficient of linear thermal respectively is 0.67 * 10-5/K and -2.39 * 10-5/K. crystal expansion coefficient decreases with the increase of pressure, which is due to the pressure flow unit of metallic glass decreases, non uniformity weakened microstructure, crystal crystal material which makes Cu rich and no Pd in phase I gradually less, and containing Pd and Cu elements base The results show that high pressure is a very unique and effective way to prepare room temperature, zero expansion and negative expansion materials. It can promote the design and application of materials, and help understand the basic problems of metallic glass and zero negative expansion materials.

【学位授予单位】：中国科学院大学(中国科学院物理研究所)
【学位级别】：博士
【学位授予年份】：2017
【分类号】：O521;TG139.8

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