本文選題：第一性原理計算 + Mg-Ca系合金��； 參考：《沈陽工業(yè)大學》2015年碩士論文

【摘要】：鎂合金具有一系列優(yōu)良的性能被廣泛應用于汽車、3C、航空航天及國防等領域。不過，由于受其自身性能的約束使得鎂合金在應用過程中受到了限制。合金化被認為是改善鎂合金性能的一種重要手段。 本文以Mg-Ca系合金為基，采用基于密度泛函理論第一性原理計算方法的CASTEP軟件包，研究合金化元素Sn、Cu、Zn、Sr與Mg-Ca系合金作用生成Mg2Sn、MgCu2、MgZn2、Mg2Sr和Mg2Ca五種AB2型金屬間化合物的結構穩(wěn)定性、力學性質(zhì)、電子結構以及德拜溫度。晶格參數(shù)的計算結果與相關文獻報道值吻合的很好。合金形成熱的結果表明，Mg2Sn的合金形成能力最強，結合能的結果表明，MgCu2的結構穩(wěn)定性最強。計算了五種AB2型金屬間化合物的彈性常數(shù)，推導了彈性模量（體模量B，剪切模量G，楊氏模量E），泊松比和各向異性系數(shù)A，計算結果表明，，Mg2Sn為脆性相，其余四種均為延性相。在五種AB2型金屬間化合物中，MgCu2剛度最大，MgZn2塑性最好。預測了五種AB2型金屬間化合物的熔點和硬度。研究了五種AB2型金屬間化合物的態(tài)密度、Mulliken電子占據(jù)數(shù)和差分電荷密度，最后計算并分析了五種AB2型金屬間化合物的德拜溫度。通過計算結果分析可知，合金化元素Sn、Cu、Zn、Sr加入到Mg-Ca系合金中可以提升合金的力學性能。 本文進一步采用第一性原理計算方法首次研究了Mg2Sr和Mg2Ca在不同壓力下的力學、電子和熱力學性質(zhì)。計算了Mg2Sr和Mg2Ca在不同壓力下的彈性常數(shù)，研究了Mg2Sr和Mg2Ca在壓力作用下的彈性模量、泊松比、柯西壓力以及彈性各向異性。計算結果表明，Mg2Sr的彈性模量、泊松比和柯西壓力，Mg2Ca的體模量和柯西壓力均隨壓力的增加而升高，Mg2Ca的剪切模量和楊氏模量則隨壓力的增加先升高后降低，二者在各自壓力研究范圍內(nèi)均為延性相，各向異性程度隨壓力增加有減小趨勢。此外，分析了在壓力作用下Mg2Sr和Mg2Ca的電子結構，研究了二者在壓力作用下的德拜溫度，以及在不同溫度和壓力下的熱力學性質(zhì)。
[Abstract]:Magnesium alloys have been widely used in automotive, aerospace, national defense and other fields with a series of excellent properties. However, magnesium alloys are restricted in application due to their properties. Alloying is regarded as an important means to improve the properties of magnesium alloys. In this paper, based on Mg-Ca alloys, the structural stability and mechanical properties of five kinds of AB _ 2-type intermetallic compounds, mg _ 2SnCu _ 2C _ 2H _ (2) mg _ (2) Zn _ (2) mg _ (2Sr) and mg _ (2CA), were studied by using CASTEP software package based on the first principle calculation method of density functional theory (DFT). Electronic structure and Debye temperature. The calculated results of lattice parameters are in good agreement with the reported values. The results of formation heat show that the formation ability of mg _ 2SN alloy is the strongest, and the binding energy shows that the structure stability of MgCu _ 2 is the strongest. The elastic constants of five AB2-type intermetallic compounds are calculated. The elastic moduli (bulk modulus B, shear modulus G, Young's modulus E ~ (1), Poisson's ratio and anisotropy coefficient A) are derived. The calculated results show that mg _ 2SN is a brittle phase, while the other four are ductile. Among the five kinds of AB _ 2 intermetallic compounds, MgCu _ 2 has the highest stiffness and the best plasticity is MgZn _ 2. The melting point and hardness of five AB 2 intermetallic compounds were predicted. The density of states and the differential charge density of five AB2-type intermetallic compounds are studied. Finally, the Debye temperature of the five AB2-type intermetallic compounds is calculated and analyzed. The results show that the mechanical properties of the alloy can be improved by adding the alloying element Sno CuCuZN Sr to the Mg-Ca alloy. In this paper, the mechanical, electronic and thermodynamic properties of mg _ 2Sr and mg _ 2Ca under different pressures have been studied for the first time by using first-principle calculation method. The elastic constants of mg _ 2Sr and mg _ 2Ca under different pressures are calculated. The elastic modulus, Poisson's ratio, Cauchy pressure and elastic anisotropy of mg _ 2Sr and mg _ 2Ca under different pressures are studied. The results show that the elastic modulus of mg _ 2Sr, Poisson's ratio and the bulk modulus and Cauchy pressure of mg _ 2Ca increase with the increase of pressure. The shear modulus and Young's modulus of mg _ 2Ca increase first and then decrease with the increase of pressure. Both of them are ductile phase in their respective pressure range, and the anisotropy tends to decrease with the increase of pressure. In addition, the electronic structures of mg _ 2Sr and mg _ 2Ca under pressure were analyzed, and the Debye temperature and thermodynamic properties of mg _ 2Sr and mg _ 2Ca at different temperatures and pressures were studied.
【學位授予單位】：沈陽工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TG146.22

【參考文獻】

相關期刊論文 前10條

1 嚴輝,楊巍,宋雪梅,呂廣宏;第一原理方法在材料科學中的應用[J];北京工業(yè)大學學報;2004年02期

2 陳國良;金屬間化合物結構材料研究現(xiàn)狀與發(fā)展[J];材料導報;2000年09期

3 李德輝;董杰;曾小勤;盧晨;丁文江;;高性能稀土鎂合金研究進展[J];材料導報;2005年08期

4 顏廷亭;譚麗麗;熊黨生;張炳春;楊柯;;醫(yī)用鎂金屬材料的研究進展[J];材料導報;2008年01期

5 程仁菊;潘復生;楊明波;湯愛濤;;鍶在鎂合金中的應用及其研究新進展[J];材料導報;2008年05期

6 王渠東 ,丁文江;鎂合金研究開發(fā)現(xiàn)狀與展望[J];世界有色金屬;2004年07期

7 陳禮清 ,趙志江;從鎂合金在汽車及通訊電子領域的應用看其發(fā)展趨勢[J];世界有色金屬;2004年07期

8 劉正,王越,王中光,李鋒,申志勇;鎂基輕質(zhì)材料的研究與應用[J];材料研究學報;2000年05期

9 黃海軍;王瑞權;趙海靜;;鎂合金新型成型工藝與應用[J];熱處理技術與裝備;2011年02期

10 陳先華;耿玉曉;劉娟;;鎂及鎂合金功能材料的研究進展[J];材料科學與工程學報;2013年01期

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