本文選題：鎳基非晶態(tài)合金 + 第一性原理模擬��； 參考：《新疆大學(xué)》2017年碩士論文

【摘要】：在本碩士論文中,我們運(yùn)用第一性原理從頭算分子動(dòng)力學(xué)計(jì)算機(jī)模擬的方法對(duì)Ni_(80)(P,B,C)_(20)非晶態(tài)合金以及含Ni的Fe_(80)P_(13)C_7非晶態(tài)合金進(jìn)行了研究,主要工作包括以下兩個(gè)部分。(1)為了研究類(lèi)金屬元素(P,B,C)對(duì)Ni基非晶態(tài)合金的原子排布結(jié)構(gòu)以及玻璃化形成能力的影響,我們選取三個(gè)典型的Ni基非晶態(tài)合金,即Ni_(80)P_(14)B_6,Ni_(80)B_(14)C_6和Ni_(80)P13C7,作為研究對(duì)象,對(duì)這三個(gè)合金從1800K逐步降溫至300K的過(guò)程進(jìn)行分子動(dòng)力學(xué)計(jì)算模擬。雙體分布函數(shù)分析結(jié)果表明,Ni_(80)P_(14)B_6和Ni_(80)P13C7這兩個(gè)非晶態(tài)合金中的Ni-P和Ni-C鍵的鍵強(qiáng)比Ni_(80)B_(14)C_6中Ni-B鍵要大,并且P-P,P-B,P-C和C-C鍵相互吸引,這有利于合金的玻璃化形成能力。相反,在Ni_(80)B_(14)C_6非晶態(tài)合金中,B-B鍵和B-C鍵有相互排斥的傾向,這不利于非晶態(tài)合金的玻璃化形成能力。通過(guò)Voronoi多面體分析技術(shù),我們發(fā)現(xiàn)P原子有兩種占位方式,一種在反棱柱團(tuán)簇的中心,另一種是在Ni原子的替換位置。相比于Ni_(80)P13C7,Ni_(80)P_(14)B_6非晶態(tài)合金中有更多以P原子為中心的類(lèi)二十面體團(tuán)簇,導(dǎo)致了更為復(fù)雜的溶體結(jié)構(gòu),這對(duì)玻璃化形成能力是有利的。通過(guò)以上分析,我們得到的結(jié)論是,這三種合金的玻璃化形成能力按照Ni_(80)P_(14)B_6,Ni_(80)P13C7和Ni_(80)B_(14)C_6的順序依次降低。(2)我們對(duì)Fe_(80)P_(13)C_7和Fe50Ni30P13C7非晶態(tài)合金進(jìn)行了第一性原理模擬計(jì)算,基此調(diào)查Ni的添加導(dǎo)致Fe_(80)P_(13)C_7塊體非晶態(tài)合金塑性得到很大提高的原因。結(jié)果表明,Fe_(80)P_(13)C_7非晶態(tài)合金中以類(lèi)二十面體團(tuán)簇結(jié)構(gòu)為主;而Fe50Ni30P13C7非晶態(tài)合金中阿基米德反棱柱團(tuán)簇的比例明顯升高,即五次對(duì)稱(chēng)性降低。相較于其它的原子配位方式,五次對(duì)稱(chēng)結(jié)構(gòu)的排列使體系更致密,具有更高的構(gòu)型轉(zhuǎn)換障礙,因而更難發(fā)生剪切轉(zhuǎn)變。因此,從短程有序中五次對(duì)稱(chēng)性的數(shù)量來(lái)看,模擬計(jì)算結(jié)果說(shuō)明Ni的添加將導(dǎo)致Fe_(80)P_(13)C_7非晶態(tài)合金塑性的提高。進(jìn)一步,通過(guò)電荷密度圖可以看到,Fe_(80)P_(13)C_7合金中的金屬-類(lèi)金屬元素之間電荷密度大于Fe50Ni30P13C7合金,這意味著,相比于Fe50Ni30P13C7,Fe_(80)P_(13)C_7非晶態(tài)合金中金屬-類(lèi)金屬元素間的鍵合有更多的共價(jià)鍵特性。相比于金屬鍵合,共價(jià)鍵的強(qiáng)度較高,這使得合金的剪切模量升高,泊松系數(shù)減小,剪切流動(dòng)阻礙變大,從而導(dǎo)致非晶態(tài)合金的塑性變差。并且,共價(jià)鍵的定域性很強(qiáng),當(dāng)塊體非晶態(tài)合金受到足夠大的應(yīng)力迫使原子間發(fā)生相對(duì)位移時(shí),將破壞它們之間的共價(jià)鍵鍵合,從而使材料發(fā)生斷裂。因此,從鍵合特性的角度考慮,模擬計(jì)算的結(jié)果同樣表明Ni的添加將導(dǎo)致Fe_(80)P_(13)C_7中非晶態(tài)合金塑性的提高。
[Abstract]:In this master's thesis, we use the first-principle ab initio molecular dynamics computer simulation method to study the amorphous alloy and the Fe_(80)P_(13)C_7 amorphous alloy containing Ni. In order to study the effect of the metal-like element PbBCon on the atomic arrangement and glass-forming ability of Ni-based amorphous alloys, we select three typical Ni-based amorphous alloys. The main work is as follows: 1) in order to study the effect of the metal-like elements on the atomic arrangement and glass-forming ability of Ni-based amorphous alloys, we select three typical Ni-based amorphous alloys. That is, Nitiao 80 / PX / P / T / C / C / C / C / C / C / C / T / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / T / C / C / C / C / C / C / C / C / C The results of the analysis of the catamorphic distribution function show that the bond strength of the Ni-P and Ni-C bonds in the two amorphous alloys, NII _ S _ T _ (80) P _ (+) _ (14) S _ (6) and Ni_(80)P13C7, is larger than that of the Ni-B bond in Ni_(80)B_(14)C_6, and that the bond is attracted to each other by the P-P _ (P) -B _ (P) -P _ (P-C) and C-C bond, which is beneficial to the glass-forming ability of the alloy. On the contrary, there is a tendency of mutual repulsion between B-B bond and B-C bond in Ni_(80)B_(14)C_6 amorphous alloy, which is not conducive to the glass forming ability of amorphous alloy. By means of Voronoi polyhedron analysis, we find that there are two kinds of occupation modes of P atom, one is in the center of antiprism cluster, the other is in the substitution position of Ni atom. There are more icosahedron clusters centered on P atoms in the amorphous alloys than in Nitig / T / P _ (80) P _ (13) C _ (7) / Ni / T _ (80) P _ (14) B _ (6) amorphous alloys, which leads to a more complex solution structure, which is beneficial to the glass-forming ability. From the above analysis, it is concluded that the vitrification capacity of the three alloys is reduced by the order of Nis / T / P / P / T / P / T / P / T / P / T / P / T / T / P / T / P / T / T / P / C / C / C / C / Ni_(80)B_(14)C_6.) We have carried out first-principles simulation calculations for Fe_(80)P_(13)C_7 and Fe50Ni30P13C7 amorphous alloys. Therefore, the addition of Ni can improve the plasticity of Fe_(80)P_(13)C_7 bulk amorphous alloy. The results show that the structure of icosahedron cluster is dominant in the C7 amorphous alloy, while the ratio of the archimedean antiprism cluster in the Fe50Ni30P13C7 amorphous alloy increases obviously, that is, the fifth symmetry decreases. Compared with other atomic coordination modes, the arrangement of quintic symmetry structure makes the system denser and has higher barrier of configuration transition, so it is more difficult to take place shear transition. Therefore, according to the number of five-order symmetry in short-range order, the simulation results show that the addition of Ni will lead to the improvement of the plasticity of Fe_(80)P_(13)C_7 amorphous alloy. Furthermore, it can be seen from the charge-density diagram that the charge density between metal-like elements is greater than that of Fe50Ni30P13C7 alloys in the Festav / PSC-13C7 alloy, which means that there are more covalent bonding properties between metal-like elements than Fe50Ni30P13C7FeS-1 P13C7 amorphous alloys. Compared with metal bonding, the strength of covalent bond is higher, which leads to the increase of shear modulus, the decrease of Poisson coefficient and the increase of shear flow hindrance, which leads to the plasticity of amorphous alloy becoming worse. Moreover, the covalent bond is very local. When the bulk amorphous alloy is subjected to enough stress to force the relative displacement between atoms, the covalent bond between them will be destroyed and the material will be broken. Therefore, from the point of view of bonding properties, the simulation results also show that the addition of Ni will lead to the improvement of the plasticity of Fe_(80)P_(13)C_7 amorphous alloys.
【學(xué)位授予單位】：新疆大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：TG139.8

【參考文獻(xiàn)】

相關(guān)博士學(xué)位論文 前1條

1 潘少鵬;Fe基合金液態(tài)及非晶態(tài)結(jié)構(gòu)的分子動(dòng)力學(xué)研究[D];山東大學(xué);2012年

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本文編號(hào)：1953257