本文選題：金屬玻璃 + 固溶體合金�。� 參考：《大連理工大學》2017年博士論文

【摘要】：本論文將針對金屬玻璃和固溶體合金的成分根源進行研究。這兩類合金在特定成分下會具有特殊的性能,這些特定成分都是經過長期大量的實驗探索而得,人們迫切需要理解其成分背后的結構根源,從而建立有效的成分設計理論,以指導合金研發(fā)。鑒于這些合金均呈現(xiàn)近程有序結構,本課題組前期工作利用團簇加連接原子模型實現(xiàn)了對近程有序結構的描述,經驗式地提出了合金具有特定的"第一近鄰團簇加若干連接原子"成分式,但是在成分式的獲得上一直存在物理基礎不明確、經驗推斷過多等缺點,包括第一近鄰的準確定義、團簇的選擇以及連接原子的定量確定。本論文將針對上述關鍵問題進行研究,通過引入電子的Friedel振蕩和球周期,完善了描述近程序結構的團簇加連接原子模型,提出了類似于分子式的合金化學結構單元,并實現(xiàn)了其定量計算。由此,本工作揭示了金屬玻璃和固溶體合金的成分根源,推出了統(tǒng)一的成分式規(guī)則,發(fā)展了合金成分設計的理論基礎。具體的工作內容涵蓋以下四個方面:(1)首先引入電子的Friedel振蕩解決第一近鄰多面體團簇的定義問題。第一近鄰的確定一直缺乏物理機制,尤其是團簇第一近鄰原子分布在多個殼層上時,團簇的截斷距離無法確定。本論文通過引入電子的Friedel振蕩機制和原子密堆判據(jù),給出了截斷距離的明確定義,并指出團簇的最近鄰殼層被Friedel振蕩勢函數(shù)中第一個最小值的范圍所限制。團簇中"中心原子-最外層原子"和"中心原子-最內層原子"的距離分別為rL和rS利用Friedel振蕩得到rL/rs的上限為1.5。隨后在硬球原子密堆的前提下,進一步將rL/rS與原子半徑比和團簇表面覆蓋構型建立關聯(lián),給出不同情況下rL/rS的比值。將rL/rS與測得的rS相乘,最終得到團簇的截斷距離,并且在常見的團簇構型中得到驗證。(2)其次,解決了進入金屬玻璃成分式的團簇的精確選擇問題。金屬玻璃相關的合金相中通常含有多個非等效的原子占位,以任一個原子占位為心都可以定義出一個團簇,從這些團簇中選取出最具代表性的主團簇是需要解決的關鍵問題。本論文強調了主團簇的兩個重要的特征:球周期性和團簇間距,同時也是金屬玻璃的兩個結構特征。利用這兩個特征給出了二元塊體金屬玻璃相關合金相中主團簇的嚴格定義,并利用這些主團簇解釋了二元塊體金屬玻璃成分,包括Cu-Zr、Cu-Hf、Ni-Nb、Ni-Ta、Al-Ca和Pd-Si體系。(3)提出了描述固溶體近程序的化學結構單元并實現(xiàn)了其定量計算。認為接近熔點的熔體與隨后形成的固溶體之間存在類似的近程序結構遺傳。通過將團簇共振模型引入到固溶體結構的中程序描述中,指出理想滿足原子間作用的團簇加連接原子成分式就是類似于分子式的化學結構單元,而作為核心近程序結構從液態(tài)遺傳到固溶體態(tài),并得到了結構單元的計算公式,Z=c ·ρa·r13,其中c為常數(shù),ρa為原子密度(單位體積原子個數(shù)),r1為團簇半徑。利用這個公式計算得到了典型FCC結構工業(yè)合金中的化學結構單元,包括二元Cu基工業(yè)合金、Ni基單晶高溫合金以及無Co馬氏體時效不銹鋼,其結果與最常用的合金牌號吻合,從而揭示出工業(yè)合金的成分根源在于具有特定結構的化學結構單元。(4)建立了具有焊料背景的Sn基共晶點的雙團簇模型。本課題組之前的工作提出了共晶液體的雙團簇模型,即共晶液體由兩個穩(wěn)定的液體結構單元構成,這兩個結構單元分別來自兩個共晶相,結構單元可以用理想金屬玻璃的團簇式表示。Sn基共晶點多靠近β-Sn一側,不能用上述雙團簇模型解釋。共晶點中Sn含量較高,因此可以假設構成共晶液體的兩個結構單元都基于β-Sn結構,這樣就可以利用上一章中固溶體結構單元的計算方法進行團簇式的計算。首先計算出β-Sn結構中的化學結構單元為[Sn-Sn10]Sn5,即配位數(shù)為10的團簇加上5個連接原子。然后將另一種元素當作溶質,根據(jù)公式Z=c·ρa·r13 計算出具體的團簇式形式。利用雙團簇成分式解析了簡單Sn基二元共晶點,包括Sn-(Ag,Au,Mg,Pb,Zn,Bi)。最后根據(jù)這些雙團簇式,解析了典型Sn基共晶釬料成分,指出多組元Sn基共晶釬料中微合金化元素的添加一般是通過對基礎二元成分進行整數(shù)個原子的替換實現(xiàn)的,從而為Sn基共晶釬料的成分設計提供了一種新的方法。
[Abstract]:This paper will research on metal glass and solid solution alloy composition of roots. The two kinds of alloy will have special properties in specific components, these specific components is through long-term experiments and exploration, the root of people need to understand the source behind the components, so as to establish the effective theory of composition design to guide, alloy research and development. In view of these alloys showed a short-range ordered structure, ourprevious work using cluster plus glue atom model for short-range ordered structure description, empirical formula proposed alloy has specific "nearest neighbor clusters with several atomic components, but the connection" in component there has been on the physical basis is not clear, too much experience and other shortcomings, including the accurate definition of the first nearest neighbor, determine the cluster selection and quantitative connection of the atoms. This paper will address. Research on the key problems, through the introduction of electronic Friedel oscillation and ball cycle, improve the structure of the program described near cluster plus glue atom model, put forward the chemical structure of alloy unit similar to the molecular formula, and realizes the quantitative calculation. Thus, this work reveals a metal glass and solid solution alloys the root, launched a unified composition rules, the development of the theoretical basis of alloy composition design. The main content covers the following four aspects: (1) the definition of the problem first introduced Friedel electron oscillation solution of first neighbor polyhedron clusters. The first neighbor has been the lack of physical mechanism, especially the first nearest neighbor cluster the distribution of atoms in multiple shell, cut distance cluster cannot be determined. This paper introduced the electronic Friedel oscillation mechanism and atomic packing criterion, given truncation distance defined, And pointed out that the cluster nearest neighbor shell is restricted by the first minimum value in the range of Friedel oscillation potential function. The cluster "central atom - the outermost atomic" and the "central atom of the innermost atomic distance were rL and rS by Friedel rL/rs of the upper limit of 1.5. oscillation was then in the hard sphere packing density the atom under the premise of further rL/rS with atomic radius ratio and cluster configuration of surface coverage, given the ratio under different conditions of rL/rS. RL/rS and rS measured by multiplying the truncation distance obtained clusters, and verified in the cluster configuration in common (2). Secondly, to solve the the precise selection problem into clusters. The composition of metallic glass alloy metal glass phase usually contains a number of non equivalent atoms occupying, with any of the atoms occupying heart can define a cluster, from these clusters in selecting the most The main cluster representative is the key problem to be solved. This paper emphasizes two important characteristics of the main clusters: Ball periodicity and cluster spacing, and two structural features is given by the metallic glass. The two features a strict definition of two yuan bulk metallic glass alloy related main phase the cluster, and use the main cluster explained two yuan bulk metallic glass components, including Cu-Zr, Cu-Hf, Ni-Nb, Ni-Ta, Al-Ca and Pd-Si system. (3) proposed chemical structure description of the unit solid solution near program and achieve its quantitative calculation. That close to the melting point and then melt the formation of solid solution are similar in genetic structure between programs through the cluster resonance model is introduced into the structure of solid solution in the program description, pointed out that the ideal meet cluster interaction and connection type atomic elements is similar to the molecular formula of chemical structure The unit, which is the core in the program structure from the liquid solid solution to the genetic body, and the calculate formula of the structural unit, Z=c p a R13, where C is a constant, a refers to the atomic density (number of atoms per unit volume), R1 as the cluster radius. Using this formula to calculate the chemical structure the typical structure of industrial unit FCC alloy, including two Cu based alloy industry, and Ni based single crystal superalloy Co maraging stainless steel, the most commonly used alloy anastomosis, so as to reveal the composition of alloy is the root of industrial chemical structure units with specific structure. (4) two clusters the model established with Sn based solder background of the eutectic point. The eutectic liquid cluster model of our group work, which is composed of two stable eutectic liquid liquid structure unit, the two units were from two eutectic phase, 緇撴瀯鍗曞厓鍙互鐢ㄧ悊鎯抽噾灞炵幓鐠冪殑鍥㈢皣寮忚〃紺，

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