本文選題：鎳基單晶高溫合金 + 蠕變　； 參考：《山東大學(xué)》2017年博士論文

【摘要】：鎳基單晶高溫合金具有優(yōu)異的蠕變性能和較好的組織穩(wěn)定性,是發(fā)動(dòng)機(jī)渦輪葉片的首選材料。本文設(shè)計(jì)六種Cr和Ru含量不同的鎳基單晶高溫合金,經(jīng)1100℃和137MPa下蠕變試驗(yàn),應(yīng)變量1%截?cái)嗪?借助掃描電子顯微鏡和透射電子顯微鏡研究合金的微觀結(jié)構(gòu),著重研究Cr和Ru單獨(dú)和交互作用下各合金的蠕變性能及影響機(jī)制,蠕變過程中位錯(cuò)的演變規(guī)律,高溫合金γ相內(nèi)錯(cuò)配位錯(cuò)、滑移位錯(cuò)、及擴(kuò)展位錯(cuò)形貌及芯部結(jié)構(gòu),γ'相超位錯(cuò)形貌、超分位錯(cuò)的位錯(cuò)鎖組態(tài)及擴(kuò)展位錯(cuò)組態(tài),蠕變過程中γ/γ'界面結(jié)構(gòu)及界面位錯(cuò)網(wǎng)結(jié)構(gòu),進(jìn)而總結(jié)鎳基單晶高溫合金蠕變過程中各類位錯(cuò)強(qiáng)化機(jī)制,是對高溫合金位錯(cuò)理論系統(tǒng)的總結(jié)和深入完善。(1)Ru元素和Cr元素單獨(dú)作用使合金內(nèi)γ'相筏排化程度增強(qiáng),γ/γ'界面處形成位錯(cuò)網(wǎng),蠕變性能提高。Ru和Cr交互作用對合金蠕變壽命的影響分為中Cr和高Cr兩種情況:中Cr(2.8wt.%)下添加Ru元素,合金蠕變壽命明顯延長;高Cr(5.6wt.%)下添加Ru元素,合金內(nèi)析出大量TCP脆性相,蠕變性能顯著降低。本研究首次對"Ru元素的添加造成合金元素的逆分配行為,抑制TCP相的析出"這一傳統(tǒng)結(jié)論提出不同意見并分析產(chǎn)生機(jī)制。對合金設(shè)計(jì)的指導(dǎo)意義為:合金中添加Ru元素時(shí)可適當(dāng)降低Cr元素的含量或者尋找Cr和Ru的最佳含量比。(2)鎳基單晶高溫合金蠕變過程中位錯(cuò)的演變規(guī)律為:蠕變第一階段初期位錯(cuò)被限制在γ相內(nèi)滑移;蠕變第一階段末期、穩(wěn)態(tài)蠕變初期,位錯(cuò)在γ/γ'界面處發(fā)生位錯(cuò)反應(yīng)形成位錯(cuò)網(wǎng);蠕變第二階段末期、第三階段初期,位錯(cuò)成對切入γ'相,形成超位錯(cuò)。(3)γ相內(nèi)錯(cuò)配位錯(cuò)通常位于γ/γ'界面,在錯(cuò)配應(yīng)力作用下產(chǎn)生,芯部表現(xiàn)為呈"V"形分布的兩個(gè){111}半原子面,芯部原子畸變復(fù)雜,可以看作兩刃型位錯(cuò)原子芯部畸變疊加的結(jié)果,位錯(cuò)強(qiáng)化依賴于a/2110型分位錯(cuò)間的反向疇界(APB)�；莆诲e(cuò)多為長位錯(cuò)線,60°混合型,位錯(cuò)段交滑移至{001}面后形成K-W鎖達(dá)到強(qiáng)化效果,多分布于γ基體水平通道和水平通道與垂直通道的交界處。擴(kuò)展位錯(cuò)短而直,通過插入一層{110}型半原子面或者{111}面的不完全滑移形成,a/6112型分位錯(cuò)間的復(fù)雜堆垛層錯(cuò)(CSF)能夠使位錯(cuò)滑移限制在某一{111}面內(nèi)達(dá)到強(qiáng)化效果。(4)γ'相位錯(cuò)(超分位錯(cuò))成對存在形成超位錯(cuò)。超分位錯(cuò)分解為Frank不全位錯(cuò)和Shockley不全位錯(cuò),Frank不全位錯(cuò)不可動(dòng),可以"鎖住"整根位錯(cuò),構(gòu)成位錯(cuò)鎖組態(tài)。超分位錯(cuò)分解為兩個(gè)Shockley不全位錯(cuò),CSF限制位錯(cuò)運(yùn)動(dòng),構(gòu)成擴(kuò)展位錯(cuò)組態(tài)。Frank不全位錯(cuò)通過插入一層{111}半原子面形成,芯部壓應(yīng)力占主體,不關(guān)于半原子面所在平面對稱。Shockley不全位錯(cuò)通過{111}面的不完全滑移形成。(5)蠕變過程中γ/γ'界面呈鋸齒形,穩(wěn)定性高,是位錯(cuò)運(yùn)動(dòng)和元素?cái)U(kuò)散共同作用的結(jié)果,能有效阻礙位錯(cuò)運(yùn)動(dòng),是高溫合金內(nèi)位錯(cuò)強(qiáng)化的另一表現(xiàn)方式。γ/γ'界面位錯(cuò)以位錯(cuò)網(wǎng)形式存在,隨蠕變過程進(jìn)行,經(jīng)四邊形位錯(cuò)網(wǎng)、六邊形位錯(cuò)網(wǎng)到類四邊形位錯(cuò)網(wǎng)演變,由疏松到細(xì)密的演變,由不穩(wěn)定向穩(wěn)定的演變,位錯(cuò)由可動(dòng)向不可動(dòng)演變。位錯(cuò)網(wǎng)空間結(jié)構(gòu)穩(wěn)定性高,滑移位錯(cuò)不易通過。其中,alOO型界面超位錯(cuò)芯部以位錯(cuò)偶極子形式分解,通過滑移-攀移機(jī)制形成。
[Abstract]:Nickel based single crystal superalloy has excellent creep properties and good microstructure stability. It is the first choice for engine turbine blades. In this paper, six kinds of nickel based single crystal superalloys with different Cr and Ru content were designed. After the creep test at 1100 and 137MPa, the strain 1% was truncated with the aid of scanning electron microscope and transmission electron microscope. The microstructure of the alloy is focused on the study of the creep properties and influence mechanism of Cr and Ru, the evolution of dislocation, dislocation dislocation, slip dislocation, dislocation morphology and core structure, gamma 'Superdislocation profile, Superdislocation dislocation lock configuration and extended dislocation configuration, In the process of creep, gamma / gamma interface structure and interface dislocation network structure are used to summarize the mechanism of dislocation strengthening during the creep process of nickel base single crystal superalloy. It is a summary and thorough improvement of the theoretical system of Superalloy dislocation theory. (1) the effect of Ru and Cr elements alone on the enhancement of the rafting degree of the gamma 'phase raft in the alloy, and the formation of dislocation networks at the gamma / gamma interface The effect of the interaction of.Ru and Cr on the creep life of.Ru and Cr is divided into two kinds of conditions: medium and high Cr: adding Ru element to Cr (2.8wt.%), the creep life of the alloy is obviously prolonged; the addition of Ru element to the high Cr (5.6wt.%) is a large amount of TCP brittle phase precipitated in the alloy, and the creep property can be significantly reduced. This study is the first time for the addition of "Ru elements" The reverse distribution of alloy elements and inhibition of the precipitation of TCP phase "this traditional conclusion puts forward different opinions and analyses the mechanism. The guiding significance of the alloy design is that when adding Ru elements in the alloy, the content of Cr elements can be reduced or the optimum content ratio of Cr and Ru is found. (2) the dislocation evolution during the creep process of the nickel base single crystal superalloy. The law is that the dislocation of the first stage of creep is confined in the phase of the gamma phase, the first stage of creep, the initial stage of the steady creep, dislocation in the gamma / gamma interface and the dislocation network at the gamma / gamma interface, the second stage of creep, the early stage of the third stage, the dislocation into the gamma phase, and the formation of Superdislocation. (3) the mismatch dislocation in the gamma phase is usually located in the gamma / gamma boundary. Under the action of mismatched stress, the core is shown to be two {111} semi atomic planes with "V" shaped distribution, and the core atomic distortion is complex. It can be regarded as the result of the superposition of the core distortion of the two edged dislocation atom, and the dislocation strengthening depends on the reverse domain boundary (APB) between the a/2110 dislocations. The slip dislocation is mostly the long dislocation line, the 60 degree mixed type, the dislocation segment intersection. After sliding to the {001} surface, the K-W lock is formed to achieve the strengthening effect, which is mostly distributed at the junction of the horizontal and horizontal channels of the gamma matrix. The extended dislocation is short and straight, and is formed by inserting a layer of {110} type semi atomic surface or the incomplete slip of the {111} surface, and the complex stacking fault (CSF) can restrict the dislocation slip between the a/6112 type dislocations. The enhancement effect is achieved in a certain {111} plane. (4) the gamma phase error (superposition dislocation) is Superdislocation. The superposition dislocations are divided into Frank incomplete dislocations and Shockley dislocations, Frank incomplete dislocations are unmovable, and the whole dislocation can be locked up to form a dislocation lock configuration. The superposition dislocations are decomposed into two Shockley incomplete dislocations and CSF limited dislocations. Motion, forming an extended dislocation configuration.Frank incomplete dislocation by inserting a layer of {111} semi atomic plane, the core pressure stress is the main body, and the plane symmetric.Shockley incomplete dislocation of the semi atomic plane is formed by the incomplete slip of the {111} surface. (5) during the creep process, the gamma / gamma interface is serrated, the stability is high, and it is dislocation movement and element expansion. The result of the scattered interaction can effectively impede dislocation movement and be another expression of dislocation strengthening in the superalloy. The dislocation of the gamma / gamma interface exists in the form of dislocation network, which evolves with the quadrangular dislocation net, hexagonal dislocation net to the quadrangular dislocation network, and the evolution from the loose to the fine-grained, from the unstable to the stable. The dislocation network has high stability, and the slip dislocation is not easy to pass through the dislocation network. Among them, the Superdislocation core of the alOO interface is decomposed in the form of dislocation dipole, and is formed by sliding climbing mechanism.

【學(xué)位授予單位】：山東大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2017
【分類號】：TG132.3

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