塊體金屬玻璃本構(gòu)關(guān)系及其多相結(jié)構(gòu)的有限元分析
發(fā)布時(shí)間：2018-11-01 14:43
【摘要】：金屬玻璃是通過快速冷卻方法獲得的非晶態(tài)合金,是一種區(qū)別于傳統(tǒng)晶態(tài)金屬合金的新型材料。金屬玻璃在原子排列上呈現(xiàn)出長程無序,短程有序的結(jié)構(gòu)特點(diǎn)。由于金屬玻璃原子排列的特殊性,因此金屬玻璃由于具有良好的物理、化學(xué)和力學(xué)性能,特別是在力學(xué)性能方面表現(xiàn)出高的壓縮強(qiáng)度、高的斷裂韌性、高的疲勞強(qiáng)度等。但其在室溫單軸拉伸或壓縮時(shí),大多數(shù)單相塊體金屬玻璃表現(xiàn)為無宏觀塑性變形的脆性斷裂,這嚴(yán)重制約著金屬玻璃作為高強(qiáng)度工程材料的應(yīng)用。為了改善金屬玻璃的室溫塑性,人們參考晶體材料的塑性提高方法來提高金屬玻璃的塑性。比如:表面處理(軋制,噴丸,激光燒蝕表面等),熱處理以及生成復(fù)合材料等來提高非晶的塑性。由于晶體與非晶的結(jié)構(gòu)不同,因此其微觀變形機(jī)制也不同。由于兩者的微觀變形機(jī)制不同,因此適用晶體材料可以提高塑性的方法,不一定對(duì)金屬玻璃有效。因此研究金屬玻璃的變形機(jī)制和其對(duì)應(yīng)的變形行為有非常重要的現(xiàn)實(shí)意義,對(duì)于提高金屬玻璃的實(shí)驗(yàn)有著很重要的理論指導(dǎo)意義�，F(xiàn)有最流行的微觀變形機(jī)制是Spaepen提出的自由體積理論。自由體積理論將自由體積作為反映材料微觀結(jié)構(gòu)的微觀變量。金屬玻璃的力學(xué)性能與其微觀結(jié)構(gòu)有著非常緊密的聯(lián)系,因此不同的初始應(yīng)力狀態(tài)或初始自由體積分布對(duì)金屬玻璃的力學(xué)性能的影響。本文主要基于自由體積理論的微觀變形機(jī)制建立金屬玻璃的宏觀本構(gòu)關(guān)系并分析其多相結(jié)構(gòu)變形行為。從材料設(shè)計(jì)的角度理解則是,建立基于自由體積理論的本構(gòu)關(guān)系,以自由體積為材料結(jié)構(gòu)參數(shù),以提高金屬玻璃塑性或力學(xué)性能為目的的材料設(shè)計(jì)和材料計(jì)算。研究金屬玻璃本構(gòu)關(guān)系及其多相結(jié)構(gòu)變形行為,尤其是剪切帶的形成和發(fā)展過程,對(duì)于提高金屬玻璃及其多相復(fù)合材料的塑性有著非常重要的理論指導(dǎo)意義。本文的主要研究內(nèi)容包括以下三個(gè)方面:第一:基于Spaepen的自由體積理論,結(jié)合宏觀變形準(zhǔn)則(Drucker-Prager屈服準(zhǔn)則),建立大塊金屬玻璃的彈塑性本構(gòu)關(guān)系。第二:基于單相大塊金屬玻璃的微觀結(jié)構(gòu),本文首次提出初始自由體積呈現(xiàn)不同統(tǒng)計(jì)分布(自由體積的分布極限區(qū)間,自由體積的均值,自由體積分布的對(duì)稱性和自由體積的分布方差)對(duì)金屬玻璃的力學(xué)性能的影響。金屬玻璃結(jié)構(gòu)的非均勻性越大越有利于其塑性。第三:基于多相金屬玻璃的微觀結(jié)構(gòu)對(duì)應(yīng)的初始自由體積的空間非均勻分布,如:漸變式自由體積梯度分布,相分離(phase separation included Spinodal decomposition and Binodal decomposition)等,分析不同的自由體積空間非均勻分布對(duì)多相塊體金屬玻璃的力學(xué)性能的影響以及相應(yīng)剪切帶的形成過程(成核-擴(kuò)展-發(fā)展-阻止-分叉-繞行等剪切帶發(fā)展行為)。通過自由體積的漸變梯度分布可知，，對(duì)于多相金屬玻璃的強(qiáng)化與剪切帶的阻止有緊密聯(lián)系,即自由體積梯度效應(yīng)(free volume gradienteffect)。Spinodal相解析式的空間分布可知剪切帶的形成不僅與最大剪切應(yīng)力有關(guān),更與自由體積的空間分布有關(guān)(微觀結(jié)構(gòu))。分析了自由體積的統(tǒng)計(jì)分布作用,Spinodal形貌的角度作用以及內(nèi)尺寸作用對(duì)Spinodal分解金屬玻璃復(fù)合材料的力學(xué)性能影響。其中角度作用(orientation effect)有利于金屬玻璃的塑性,而內(nèi)稟尺寸效應(yīng)(intrinsic size effect)遵循最小尺寸兼容原則(minimum size compatibility principle),即當(dāng)相分離結(jié)構(gòu)的尺寸大于最小剪切帶變形尺寸,其相解析內(nèi)稟尺寸效應(yīng)不起作用。同時(shí)分析Binodal相解析的顆粒增強(qiáng)相的尺寸,體百分比和種類以及金屬玻璃基體種類(matrix effect)對(duì)多相金屬玻璃的力學(xué)性能影響。
[Abstract]:Metallic glass is an amorphous alloy obtained by rapid cooling method, which is a kind of new material which is different from traditional crystalline metal alloy. Metal glasses exhibit long-range disorder, short-range and orderly structure characteristics in atomic arrangement. Because of the particularity of metal glass atomic arrangement, the metal glass exhibits high compressive strength, high fracture toughness, high fatigue strength, etc. due to its good physical, chemical and mechanical properties. However, most of the single-phase bulk metallic glasses exhibit a brittle fracture without macroscopic plastic deformation at room temperature uniaxial tension or compression, which severely restricts the application of metal glass as high-strength engineering materials. In order to improve the room temperature plasticity of the metal glass, the plasticity of the metal glass is improved by the plastic improvement method of the crystal material. such as surface treatment (rolling, shot peening, laser ablation surface, etc.), heat treatment, and formation of composite materials, etc. Because the crystal is different from the amorphous structure, its micro-deformation mechanism is different. Because of the different micro-deformation mechanism, the application of the crystal material can improve the plasticity and not be effective for the metal glass. Therefore, it is very important to study the deformation mechanism of metal glass and its corresponding deformation behavior. The most popular micro-deformation mechanism is the free volume theory proposed by Spaepen. The free volume theory takes the free volume as a microscopic variable that reflects the microstructure of the material. The mechanical properties of the metal glass are closely related to their microstructure, so different initial stress states or initial free volume distributions affect the mechanical properties of the metal glass. In this paper, based on the micro-deformation mechanism of free volume theory, the macro-structure relation of metal glass is established and its multiphase structure deformation behavior is analyzed. It is understood from the viewpoint of material design that this structure is based on the free volume theory, and the free volume is the structural parameter of the material, so as to improve the plastic or mechanical properties of the metal. It is very important to study the structure of metal glass and its multiphase structure deformation behavior, especially the formation and development of shear zone. The main contents of this paper include the following three aspects: first, based on Spaepen's free volume theory, combining with the macro deformation criterion (Drucker-Prager yield criterion), the elastic-plastic constitutive relation of bulk metallic glass is established. Secondly, based on the microstructure of single-phase bulk metallic glass, the initial free volume presented in this paper presents the distribution limit of free volume and the mean value of free volume for the first time. The symmetry of free volume distribution and the distribution variance of free volume influence the mechanical properties of metal glass. The larger the non-uniformity of the metal glass structure is, the greater the plasticity thereof. Third, the spatial non-uniform distribution of the initial free volume corresponding to the microstructure of the multi-phase metal glass, such as gradient free volume gradient distribution, phase separation and the like, The effects of non-uniform distribution of free volume on the mechanical properties of multi-phase bulk metallic glass and the formation of corresponding shear bands (nucleation-expansion-development-prevention-bifurcation-detour, etc.) were analyzed. From the gradient distribution of free volume, it can be seen that the strengthening of multi-phase metal glass is closely related to the blocking of shear zone, i. e. free volume gradient effect. The spatial distribution of Spinodal phase analysis shows that the formation of shear zone not only relates to the maximum shear stress, but also relates to the spatial distribution of free volume (microstructure). The statistical distribution of free volume, the angle of Spinodal morphology and the effect of inner dimension on the mechanical properties of Spinodal decomposition metal glass composites were analyzed. The angle effect is beneficial to the plasticity of the metal glass, while the intrinsic size effect follows the minimum size compatibility principle, that is, when the size of the phase separation structure is larger than the minimum shear band deformation size, the intrinsic size effect in the phase analysis does not work. At the same time, the size, volume percentage and kind of particle reinforced phase resolved by Bindal phase and the influence of matrix effect on the mechanical properties of multiphase metal glass were analyzed.
【學(xué)位授予單位】：北京科技大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2017
【分類號(hào)】：TG139.8
本文編號(hào)：2304234
[Abstract]:Metallic glass is an amorphous alloy obtained by rapid cooling method, which is a kind of new material which is different from traditional crystalline metal alloy. Metal glasses exhibit long-range disorder, short-range and orderly structure characteristics in atomic arrangement. Because of the particularity of metal glass atomic arrangement, the metal glass exhibits high compressive strength, high fracture toughness, high fatigue strength, etc. due to its good physical, chemical and mechanical properties. However, most of the single-phase bulk metallic glasses exhibit a brittle fracture without macroscopic plastic deformation at room temperature uniaxial tension or compression, which severely restricts the application of metal glass as high-strength engineering materials. In order to improve the room temperature plasticity of the metal glass, the plasticity of the metal glass is improved by the plastic improvement method of the crystal material. such as surface treatment (rolling, shot peening, laser ablation surface, etc.), heat treatment, and formation of composite materials, etc. Because the crystal is different from the amorphous structure, its micro-deformation mechanism is different. Because of the different micro-deformation mechanism, the application of the crystal material can improve the plasticity and not be effective for the metal glass. Therefore, it is very important to study the deformation mechanism of metal glass and its corresponding deformation behavior. The most popular micro-deformation mechanism is the free volume theory proposed by Spaepen. The free volume theory takes the free volume as a microscopic variable that reflects the microstructure of the material. The mechanical properties of the metal glass are closely related to their microstructure, so different initial stress states or initial free volume distributions affect the mechanical properties of the metal glass. In this paper, based on the micro-deformation mechanism of free volume theory, the macro-structure relation of metal glass is established and its multiphase structure deformation behavior is analyzed. It is understood from the viewpoint of material design that this structure is based on the free volume theory, and the free volume is the structural parameter of the material, so as to improve the plastic or mechanical properties of the metal. It is very important to study the structure of metal glass and its multiphase structure deformation behavior, especially the formation and development of shear zone. The main contents of this paper include the following three aspects: first, based on Spaepen's free volume theory, combining with the macro deformation criterion (Drucker-Prager yield criterion), the elastic-plastic constitutive relation of bulk metallic glass is established. Secondly, based on the microstructure of single-phase bulk metallic glass, the initial free volume presented in this paper presents the distribution limit of free volume and the mean value of free volume for the first time. The symmetry of free volume distribution and the distribution variance of free volume influence the mechanical properties of metal glass. The larger the non-uniformity of the metal glass structure is, the greater the plasticity thereof. Third, the spatial non-uniform distribution of the initial free volume corresponding to the microstructure of the multi-phase metal glass, such as gradient free volume gradient distribution, phase separation and the like, The effects of non-uniform distribution of free volume on the mechanical properties of multi-phase bulk metallic glass and the formation of corresponding shear bands (nucleation-expansion-development-prevention-bifurcation-detour, etc.) were analyzed. From the gradient distribution of free volume, it can be seen that the strengthening of multi-phase metal glass is closely related to the blocking of shear zone, i. e. free volume gradient effect. The spatial distribution of Spinodal phase analysis shows that the formation of shear zone not only relates to the maximum shear stress, but also relates to the spatial distribution of free volume (microstructure). The statistical distribution of free volume, the angle of Spinodal morphology and the effect of inner dimension on the mechanical properties of Spinodal decomposition metal glass composites were analyzed. The angle effect is beneficial to the plasticity of the metal glass, while the intrinsic size effect follows the minimum size compatibility principle, that is, when the size of the phase separation structure is larger than the minimum shear band deformation size, the intrinsic size effect in the phase analysis does not work. At the same time, the size, volume percentage and kind of particle reinforced phase resolved by Bindal phase and the influence of matrix effect on the mechanical properties of multiphase metal glass were analyzed.
【學(xué)位授予單位】：北京科技大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2017
【分類號(hào)】：TG139.8
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