【摘要】：金屬熔體的粘度體現了金屬熔體中原子的運動,直觀反映了金屬熔體的流動性,進而可以表現出金屬熔體中的傳熱與傳質,因此,通過研究金屬熔體的粘度有利于深入把握金屬熔體的凝固行為,調控金屬熔體的成型能力,以獲得高性能的成型金屬;金屬熔體的粘度可以從宏觀上表現液態(tài)金屬微觀結構的轉變,因此,通過研究金屬熔體的粘度可以分析液態(tài)金屬內部結構的變化;金屬熔體粘度與溫度的變化率就是金屬熔體的脆性,而脆性與合金的非晶形成能力直接相關,因此,金屬熔體的粘度可以預判合金的非晶形成能力。金屬熔體粘度的研究對于熔融金屬的基礎理論研究和科學應用都具有十分重要的指導意義。金屬鎵是一種低熔點的耐腐蝕性極好的半金屬材料。鎵合金作為一種半導體材料,在微波通信行業(yè),磁性材料,太陽能電池,醫(yī)學以及光電工業(yè)等各個方面均具有非常廣泛的應用。近年來,鎵合金作為一種新型材料在諸多領域均有較大的應用前景。本文以鎵基合金熔體為主要的研究對象,并用附帶水平磁場的高溫熔體粘度儀研究了磁場對金屬熔體粘度的影響,建立定量描述磁場與金屬熔體粘度之間的理論模型;探索磁場對Ga基金屬熔體非晶形成能力的影響;并利用分子動力學模擬計算了 Ga基金屬熔體結構,探索磁場對金屬熔體粘度的影響機制,從微觀原子角度解釋磁場下金屬熔體粘度變化的原因,為液態(tài)金屬的理論研究奠定了基礎。研究表明,Sn_(97)Fe_3、Sn_(94)Fe_6、Sn_(95)Co_5、Sn_(95)Mn_5、Al_(97)Ni_3、Al_(92)Ni_8、Ga_(98)Fe_2以及Ga_(98)Cr_2等金屬熔體的粘度在磁場下均隨著溫度的升高而減小,且都符合Arrhenius公式,指前因子隨著磁場強度的增加而不斷增加;它們的粘度在磁場下都符合二次函數式ηB=η+2H/πΩB2,金屬熔體在磁場下的粘度正比于磁場強度的平方。Ga_(80)Fe_(20),Ga_(80)Co_(20),Ga_(80)Ni_(20)以 Ga_(80)Cr_(20)合金熔體在水平磁場下的粘度均符合Arrhenius公式,隨著溫度的升高而不斷減小;并且隨著磁場強度的增加而增加;它們的過熱脆性隨著磁場強度的增加先減小后增大,最后再減小,這是由磁場對熵的影響以及磁力的影響共同決定的;不加磁場時,Ga_(80)Fe_(20),Ga_(80)Co_(20),Ga_(80)Ni_(20)以及Ga_(80)Cr_(20)合金熔體的過熱脆性隨著各個熔體的液相線溫度升高而減小;在Ga_(80)Ni_(20)和Ga_(80)Cr_(20)合金熔體中,過熱脆性值較小,而Ga_(80)Fe_(20)和Ga_(80)Co_(20)合金熔體中,過熱脆性較大。用分子動力學模擬的方法計算了 Ga_(80)Fe_(20),Ga_(80)Co_(20),Ga_(80)Ni_(20)以及Ga_(80)Cr_(20)合金熔體的液態(tài)結構,在Ga_(80)Co_(20)和Ga_(80)Ni_(20)合金熔體中,Co原子以及Ni原子被Ga原子包圍,形成中程有序結構;在Ga_(80)Fe_(20)合金熔體中,Fe原子和Ga原子隨機分布;而在Ga_(80)Cr_(20)合金熔體中,Cr原子與Cr原子之間形成了團簇,并且這個團簇有相互分離的趨勢;Ga_(80)Ni_(20),Ga_(80)Cr_(20),Ga_(80)Co_(20),Ga_(80)Fe_(20)合金熔體的粘度對磁場的響應逐漸減弱,這是由金屬熔體中的團簇大小以及磁場下粒子間的相互力引起的。
[Abstract]:The viscosity of the metal melt reflects the movement of the atoms in the metal melt, and the fluidity of the metal melt is directly reflected, so that the heat transfer and the mass transfer in the metal melt can be expressed, The forming ability of the metal melt is regulated so as to obtain the high-performance forming metal; the viscosity of the metal melt can be changed from the macroscopic to the transition of the microstructure of the liquid metal; therefore, the change of the internal structure of the liquid metal can be analyzed by studying the viscosity of the metal melt; The rate of change of the viscosity and temperature of the metal melt is the brittleness of the metal melt, and the brittleness is directly related to the amorphous forming ability of the alloy, so the viscosity of the metal melt can pre-judge the amorphous forming ability of the alloy. The research of the metal melt viscosity is of great significance to the basic theory research and the scientific application of the molten metal. The metal base material is a semi-metallic material having a low melting point and excellent corrosion resistance. As a kind of semiconductor material, the metal alloy has a very wide application in the microwave communication industry, the magnetic material, the solar cell, the medicine and the photoelectric industry. In recent years, the alloy as a kind of new material has great application prospect in many fields. In this paper, the influence of the magnetic field on the viscosity of the metal melt is studied by using a high-temperature melt viscosity meter with a horizontal magnetic field, and a theoretical model for quantitatively describing the viscosity of the magnetic field and the metal melt is established. The influence of the magnetic field on the amorphous forming ability of the Ga-based melt is explored, and the mechanism of the influence of the magnetic field on the viscosity of the metal melt is studied by using the molecular dynamics, and the cause of the change of the viscosity of the metal melt under the magnetic field is explained from the micro-atomic angle. The foundation is laid for the theoretical study of liquid metal. The results show that the viscosity of Sn _ (97) Fe _ 3, Sn _ (94) Fe _ 6, Sn _ (95) Co _ 5, Sn _ (95) Mn _ 5, Al _ (97) Ni _ 3, Al _ (92) Ni _ 8, Ga _ (98) Fe _ 2 and Ga _ (98) Cr _ 2 is reduced with the increase of the temperature in the magnetic field, and it is in accordance with the Arrhenius formula. The viscosity of the metal melt in the magnetic field is in accordance with the quadratic function type B = 1 + 2H/ 1惟 B2, and the viscosity of the metal melt under the magnetic field is directly proportional to the square of the magnetic field strength. The viscosity of Ga _ (80) Fe _ (20), Ga _ (80) Co _ (20), Ga _ (80) Ni _ (20) in the horizontal magnetic field of Ga _ (80) Cr _ (20) alloy is in accordance with the Arrhenius formula, and increases with the increase of the magnetic field strength; their overheat brittleness increases with the increase of the magnetic field strength, and finally decreases, It is determined by the influence of the magnetic field on the entropy and the influence of the magnetic force; when the magnetic field is not applied, the superheat brittleness of the Ga _ (80) Fe _ (20), Ga _ (80) Co _ (20), Ga _ (80) Ni _ (20) and the Ga _ (80) Cr _ (20) alloy melt decreases with the temperature of the liquid-phase line of each melt; in the Ga _ (80) Ni _ (20) and Ga _ (80) Cr _ (20) alloy melt, the superheat brittleness value is small, In the melt of Ga _ (80) Fe _ (20) and Ga _ (80) Co _ (20), the overheat brittleness is high. The liquid structure of Ga _ (80) Fe _ (20), Ga _ (80) Co _ (20), Ga _ (80) Ni _ (20) and Ga _ (80) Cr _ (20) alloy melt is calculated by molecular dynamics simulation. Co atoms and Ni atoms are surrounded by Ga atoms in Ga _ (80) Co _ (20) and Ga _ (80) Ni _ (20) alloy melt to form a medium-range ordered structure; in the Ga _ (80) Fe _ (20) alloy melt, the Fe atoms and Ga atoms are randomly distributed; In a Ga _ (80) Cr _ (20) alloy melt, a cluster of clusters is formed between the Cr atom and the Cr atom, and the clusters have a tendency to separate from each other; Ga _ (80) Ni _ (20), Ga _ (80) Cr _ (20), Ga _ (80) Co _ (20), Ga _ (80) Fe _ (20) alloy melt have a gradual decrease in the response of the magnetic field, this is caused by the cluster size in the metal melt and the mutual force between the particles in the magnetic field.
【學位授予單位】：山東大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TG111.4

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