發(fā)布時間：2018-02-10 13:44

  本文關鍵詞： 金屬玻璃 β弛豫 高壓 穩(wěn)定性 玻色峰 熱膨脹　出處：《中國科學院大學(中國科學院物理研究所)》2017年博士論文　論文類型：學位論文

【摘要】：弛豫一直是非晶態(tài)材料的基本問題,也一直是非晶材料研究的熱點方向。本文首先研究了金屬玻璃的β弛豫行為。不同于大多數金屬玻璃體系,我們制備出的LaGa基三元金屬玻璃具有明顯的β弛豫峰。我們用鎵元素分別替代鑭、鈷和鎳這三種元素,都發(fā)現隨著鎵元素含量的增加,β弛豫峰越來越明顯。通過應力弛豫方法,研究了鎵含量不同的金屬玻璃的應力弛豫行為,得出了它們的非均勻性和流變單元的的演變規(guī)律。由于鎵元素的熔點非常低,在近室溫鎵原子可以被看出是類液體原子,是金屬玻璃的流變單元主要組成。通過流變單元模型很好的解釋了鎵元素對金屬玻璃的β弛豫行為的影響。具有明顯β弛豫峰的LaGa基金屬玻璃可以作為模型體系研究金屬玻璃的弛豫和塑性機理。高壓是調節(jié)材料結構和性能有效的手段。在Pd40.16Ni9.64Cu30.12P20.08金屬玻璃中,通過室溫高壓的方法制備出了超穩(wěn)定大塊金屬玻璃。超穩(wěn)定金屬玻璃具有更高的玻璃轉變溫度和晶化溫度,表現出更高的動力學穩(wěn)定性。超穩(wěn)定金屬玻璃同時還具有更高的密度和硬度。即使將超穩(wěn)定玻璃進行升溫至過冷液相區(qū)處理,它依然保持著原來的穩(wěn)定性,說明它具有很高的熱穩(wěn)定性。通過調節(jié)壓力,研究了金屬玻璃的穩(wěn)定性、硬度和密度的演變規(guī)律,發(fā)現它們都隨壓力單調增加。這一結果說明高壓是制備高穩(wěn)定性和性能的大塊金屬玻璃非常獨特和有效的手段,可以推動金屬玻璃的設計和理解金屬玻璃基本問題。玻色峰一直是非晶材料重要的低溫物性。我們研究了高壓和退火對典型金屬玻璃的玻色峰和熱膨脹的影響。在退火過程中,我們發(fā)現玻色峰強度和線性熱膨脹系數表現出單調衰減行為,而在高壓下,玻色峰強度和線性熱膨脹系數都先減小后增加。在高壓下和退火過程中,玻色峰強度和線性熱膨脹系數都表現出了明確的線性關系。這種線性關系說明了玻色峰與非簡諧振動有直接的關聯,并提供了清晰的圖像深入地理解玻色峰的本質。為了探索具有室溫和高溫的零膨脹和負膨脹材料。我們研究了壓力對材料熱膨脹性能的影響。先通過室溫高壓方法調節(jié)了金屬玻璃的微觀結構,后將金屬玻璃進行晶化處理,我們制備出了正膨脹、近零膨脹和負膨脹材料。通過調節(jié)壓力,Pd40.16Ni9.64Cu30.12P20.08晶體材料的熱膨脹系數可以在1.49×10-5/K到-2.93×10-5/K范圍內可控的調節(jié),可以實現零膨脹。近零膨脹和負膨脹材料在室溫到553 K溫區(qū)內的平均線性膨脹系數分別是0.67×10-5/K和-2.39×10-5/K。晶體的線性熱膨脹系數隨著壓力的升高而逐漸減小,是由于壓力使得金屬玻璃的流變單元減少,微觀結構非均勻性減弱,從而使得晶體材料中富Cu而無Pd的析出晶體相Ⅰ逐漸較少,而含有Pd和Cu元素的基底晶體相Ⅱ逐漸增多。這一結果說明高壓是制備室溫和高溫零膨脹和負膨脹材料非常獨特和有效的手段,可以推動材料的設計和應用,和幫助理解金屬玻璃和零負膨脹材料的基本問題。
[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.

【學位授予單位】：中國科學院大學(中國科學院物理研究所)
【學位級別】：博士
【學位授予年份】：2017
【分類號】：O521;TG139.8

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本文編號：1500651