發(fā)布時間：2018-03-31 12:29

  本文選題：高鈮TiAl合金　切入點：蠕變　出處：《北京科技大學》2016年博士論文

【摘要】：高鈮TiAl合金以其優(yōu)異的高溫力學性能和較低的密度在航空、航天以及汽車發(fā)動機等領(lǐng)域顯示了巨大的發(fā)展?jié)摿?是Ni基高溫合金潛在的替代材料。目前,高鈮TiAl合金已被列為我國重點發(fā)展的航空發(fā)動機材料之一,受到了國家“973”及軍工“863”項目的資助,其在成分設(shè)計、組織控制、制備成型以及加工焊接等方面取得了一系列進展,但在性能表征以及可靠性評估方面的研究還不夠充分,尤其是在高溫服役條件下,由疲勞和蠕變交互作用引起的損傷失效則更缺乏深入系統(tǒng)的研究,嚴重影響了該合金的進一步應(yīng)用和設(shè)計開發(fā)。基于上述研究背景,本文圍繞近片層組織高鈮TiAl合金的高溫疲勞—蠕變交互作用對其相關(guān)的高溫力學性能展開了研究。具體內(nèi)容包括高溫拉伸及斷裂韌性的研究、高溫蠕變性能的研究、高溫疲勞性能的研究以及高溫疲勞—蠕變交互作用的研究。主要結(jié)論如下：高鈮TiAl合金的高溫拉伸性能和斷裂韌性受顯微組織和裂紋萌生及擴展行為的影響。SEM原位觀察及斷口觀察表明,近片層組織的高鈮TiAl合金在拉伸過程中裂紋主要在片層團界處萌生并且沿著片層團界擴展,相反,全片層組織在拉伸過程中裂紋主要在片層界面處萌生并且沿著片層界面擴展。由于裂紋沿晶界萌生和擴展降低了局部的應(yīng)力集中,因此近片層組織的拉伸性能優(yōu)于全片層組織。而由于裂紋沿晶界擴展的阻力小于裂紋沿片層界面或穿片層界面擴展的阻力,因此表現(xiàn)出近片層組織的斷裂韌性低于全片層組織的特點。高鈮TiAl合金的高溫蠕變性能研究結(jié)果表明,隨著溫度或蠕變應(yīng)力的增加,其最小蠕變速率(εmin)增加,蠕變壽命(Tr)降低。其蠕變的壽命預(yù)測公式為：logTr(h)+0.94×logεmin(%/h)=0.07SEM原位觀察表明,其蠕變變形的三階段與裂紋的萌生、擴展及相互連接相互對應(yīng)。在穩(wěn)態(tài)蠕變階段主要表現(xiàn)為裂紋的萌生和擴展,而在加速擴展階段則主要表現(xiàn)為裂紋的相互連接。微觀機制分析表明,對應(yīng)于不同的應(yīng)力水平,其蠕變變形機制不同：低應(yīng)力區(qū)為晶格擴散,中等應(yīng)力區(qū)為位錯滑移、高應(yīng)力區(qū)為孿晶變形。高鈮TiAl合金在高溫疲勞變形時,應(yīng)力比(R)對其疲勞壽命及變形機制有顯著的影響。當0.1≤R≤0.4時,疲勞壽命(NT)受疲勞—蠕變交互作用控制,表現(xiàn)為極小值特征,其壽命預(yù)測公式為其中,σa為循環(huán)應(yīng)力幅,σm為平均應(yīng)力。當0.4≤R≤1時,疲勞壽命(Nf)由蠕變變形控制,并且隨R增加N減小。其相應(yīng)的壽命預(yù)測公式為：Nf=1.17×1020σm-5.46SEM原位觀察表明,隨著R的增加,疲勞斷裂方式由R=0.1時的穿晶開裂轉(zhuǎn)變?yōu)镽=0.2和0.3時的穿晶和沿晶混合開裂,再到R≥0.4時的沿晶開裂。相應(yīng)地,微觀機制分析表明,疲勞變形機制由位錯滑移和位錯攀移轉(zhuǎn)變?yōu)槲诲e滑移和孿晶變形,再轉(zhuǎn)變?yōu)閷\晶變形。并且,加載頻率對其疲勞性能也有一定的影響作用。隨著加載頻率(D的降低,疲勞斷裂方式由f=10 Hz和1 Hz時的穿晶開裂轉(zhuǎn)變?yōu)閒=0.05 Hz和0.025 Hz時的沿晶和穿晶開裂；相應(yīng)地,疲勞變形機制由位錯滑移和位錯攀移轉(zhuǎn)變?yōu)閷\晶變形和位錯滑移。不同加載頻率下的疲勞壽命公式為：Nf=118887.96(f)1.01高鈮TiAl合金疲勞—蠕變交互作用研究表明,隨著有效保載時間(△t/tp)的增加,其壽命(Nf)呈線性降低。其相應(yīng)的壽命預(yù)測公式為：Nf=N10-Ktp/ΔtSEM原位觀察表明,隨著有效保載時間的增加,裂紋在片層團界面處的萌生幾率明顯增大,并且其裂紋擴展方式與純疲勞和純?nèi)渥冏冃螘r的裂紋擴展方式顯著不同,表現(xiàn)為混合的裂紋擴展特征。這種混合的裂紋擴展特征加速了裂紋的擴展速率,導致其壽命急劇下降。微觀機制分析表明,位錯滑移和孿晶變形共存是其疲勞—蠕變交互作用的典型特征。
[Abstract]:High Nb TiAl alloy with excellent mechanical properties at high temperature and low density in aviation, aerospace and automotive engine fields show a great potential for development, is the substitute of Ni based high temperature alloy potential. At present, the high Nb TiAl alloy has been listed as one of our focus on the development of aero engine materials by the national "973" and "863" military funded project, the organization control in the composition design, preparation, molding and welding processing has made a series of progress, but the study of characterization and reliability evaluation is not enough, especially the service conditions at high temperatures, caused by the action of fatigue and creep interaction the damage is more a lack of systematic research, has seriously affected the further application of the alloy design and development. Based on the above research background, this paper focuses on the high temperature nearly lamellar microstructure of high Nb TiAl alloy. High temperature fatigue creep interaction on the mechanical properties of the studied. The specific contents include research on high temperature tensile and fracture toughness, creep property research, study of high temperature fatigue properties and fatigue creep interaction. The main conclusions are as follows: the high temperature tensile properties and fracture toughness of high Nb TiAl alloy the microstructure and crack initiation and propagation behavior of the influence that.SEM in situ observation and fracture observation, the crack of high Nb TiAl alloy near lamellar structure during stretching mainly in the lamellar boundary of initiation and expand, lamellar along circles instead, lamellar microstructure under tensile deformation mainly in the lamellar interface the initiation and propagation along lamellar interface. The crack initiation and propagation along grain boundaries reduces the local stress concentration, so nearly lamellar microstructure tensile performance is better than that of FL group Fabric. Because the cracks propagate along the grain boundaries of the resistance is less than crack along lamellar interface or lamellar interface extended wear resistance, thus showing near the fracture toughness of microstructure than lamellar microstructure characteristics. The creep properties of high Nb TiAl alloy shows that with the increase of temperature and creep stress, the minimum creep rate (min) increased, the creep life (Tr) decreased. The creep life prediction formula: logTr (H) +0.94 * log e min (%/h) =0.07SEM in situ observation shows that the three stage and the crack initiation of creep deformation, expansion and mutual connection mutual corresponding in steady-state creep stage. Mainly for the initiation and propagation of cracks in the accelerated expansion stage is mainly connected to crack. The microscopic mechanism analysis showed that correspond to different levels of stress, the creep deformation mechanism is different: the low stress region for lattice diffusion, medium Stress is dislocation slip, high stress area is twin deformation. The high Nb TiAl alloy in high temperature fatigue deformation, stress ratio (R) has a significant effect on the deformation mechanism and its fatigue life. When R = 0.1 ~ 0.4, the fatigue life (NT) under the control of fatigue creep interaction. For the minimum feature, the life prediction formula for the sigma a cyclic stress amplitude, sigma m is the average stress. When R = 0.4 ~ 1, the fatigue life (Nf) controlled by creep deformation, and with the increase of R N decreases. The corresponding fatigue life prediction formula: Nf=1.17 * 1020 m-5.46SEM in situ observation showed that with the increase of R, the fatigue fracture mode by R=0.1 transgranular cracking into R=0.2 and 0.3 of transgranular and intergranular cracking mixture, and then to R more than 0.4 of the intergranular cracking. Accordingly, the micro mechanism analysis showed that the mechanism of fatigue deformation by dislocation slip and dislocation transfer to climb dislocation slip and twinning And then to the deformation, deformation twinning and loading frequency have certain effect on the fatigue performance. With the loading frequency (D decreased by f=10 Hz and fatigue fracture mode 1 Hz transgranular cracking into crystal cracking; f=0.05 Hz and 0.025 Hz in intergranular and accordingly. The mechanism of fatigue deformation by dislocation slip and dislocation climb into the fatigue life formula of deformation twinning and dislocation slip. Under different loading frequencies were as follows: Nf=118887.96 (f) on the interaction of fatigue and creep - 1.01 high Nb TiAl alloy shows that, with the effective holding time (t/tp) increased linearly with its life (Nf) reduced. The corresponding fatigue life prediction equation: Nf=N10-Ktp/ tSEM in situ observation showed that with the increase of effective holding time, crack initiation at the lamellar interface rate increases obviously, and the crack and deformation of pure fatigue and pure creep When the crack propagation of different performance for mixed crack propagation characteristics. This kind of mixed crack propagation characteristics of accelerated crack propagation rate, resulting in a sharp decline in life expectancy. The microscopic mechanism analysis showed that the dislocation slip and deformation twinning is a typical feature of the coexistence of fatigue creep interaction.

【學位授予單位】：北京科技大學
【學位級別】：博士
【學位授予年份】：2016
【分類號】：TG146.2

【相似文獻】

相關(guān)期刊論文 前10條

1 ;DIFFUSION BONDING OF TiAl TO Ti AND TC4 ALLOY[J];Acta Metallurgica Sinica(English Letters);2000年01期

2 ;A STUDY ON ALUMINIDE COATINGS ON TiAl ALLOYS BY PACKCEMENTATION METHOD[J];Acta Metallurgica Sinica(English Edition);2000年06期

3 ;Effects of HIPing Pressure on Microstructures and Properties of TiAl Alloy[J];Journal of Central South University of Technology(English Edition);2000年03期

4 唐建成,黃伯云,劉文勝,賀躍輝;Microstructural evolution of a forged TiAl based alloy during heat treatment at subtransus temperature[J];Transactions of Nonferrous Metals Society of China;2000年02期

5 ;Diffusion Bonding between TiAl Based Alloys and Steels[J];Journal of Materials Science & Technology;2001年01期

6 ;THE STRUCTURE CHANGE OF γ-TiAl IRRADIATED BY 50keV XENON IONS AT ROOM TEMPERATURE[J];Acta Metallurgica Sinica(English Edition);2001年04期

7 吳引江;制造TiAl薄板的新方法[J];鈦工業(yè)進展;2001年05期

8 ;Distribution of Nb atom in the TiAl+Nb system[J];Rare Metals;2001年01期

9 ;MEAM Potential with Angular Dependence for TiAl[J];Rare Metals;2001年01期

10 ;Influence of Aluminum Content in γ-TiAl with L1_0 Structure during Ordering Processes[J];Rare Metals;2001年04期

相關(guān)會議論文 前10條

1 ;Study on aging phase transformation process in Ni_(42) CrTiAl alloys[A];第二屆全國掃描電子顯微學會議論文集[C];2001年

2 Xiang Zan;Li Ouyang;Yu Wang;Yuehui He;Yong Liu;Weidong Song;;Microstructure Evolution of TiAl under Tensile Impact Loadings[A];中國材料大會2012第15分會場：TiAl合金及先進結(jié)構(gòu)金屬間化合物材料論文集[C];2012年

3 Fan Yang;Xiao Li;Nan Tian;Yongfeng Liang;Junpin Lin;;Effect of Nb Addition on the Corrosion Behavior of Porous TiAl Based Alloys in Aqueous Environments[A];中國材料大會2012第15分會場：TiAl合金及先進結(jié)構(gòu)金屬間化合物材料論文集[C];2012年

4 Zhiyong Xue;YuanXun Huang;Yongtian Wang;Xiaojing Hai;;Laser Remelting Effect on the Joint Property of Diffusion Bonding of TiAl Intermetallics and TC4 Alloy[A];中國材料大會2012第15分會場：TiAl合金及先進結(jié)構(gòu)金屬間化合物材料論文集[C];2012年

5 劉辛;駱接文;謝煥文;蔡一湘;;惰性氣體霧化法制備TiAl_3粉末的特性[A];第十四屆全國鈦及鈦合金學術(shù)交流會論文集（上冊）[C];2010年

6 Na Liu;Zhou Li;Guoqing Zhang;Hua Yuan;Wenyong Xu;Zhengjiang Gao;;Effect of Heat Treatment on the Microstructure and Property of TiAl Alloys Prepared by Gas Atomization Powders[A];中國材料大會2012第19分會場：高溫合金論文集[C];2012年

7 ;Influence of Heat Treatment on The Precipitation of γ1 Phase in High Nb Containing TiAl-based Intermetallic Alloys[A];2011中國材料研討會論文摘要集[C];2011年

8 Chuanyun Wang;Jinshan Li;Bin Tang;Hongchao Kou;;Numerical Analysis of Superplastic Bulging Process of TiAl Sheet[A];中國材料大會2012第15分會場：TiAl合金及先進結(jié)構(gòu)金屬間化合物材料論文集[C];2012年

9 孟祥康;洪建明;劉毅;趙曉寧;劉治國;;二相TiAl基金屬間化合物層片結(jié)構(gòu)中的位錯組態(tài)[A];第八次全國電子顯微學會議論文摘要集（Ⅱ）[C];1994年

10 Qing Ye;Zhimeng Guo;Qikai Duan;Chunlei Yang;Junjie Hao;;Preparation of TiAl Intermetallic Alloy by Gelcasting[A];中國材料大會2012第15分會場：TiAl合金及先進結(jié)構(gòu)金屬間化合物材料論文集[C];2012年

相關(guān)重要報紙文章 前1條

1 中航工業(yè)黎明航空發(fā)動機（集團）有限責任公司 汪大成;鈦鋁合金(TiAl)應(yīng)用現(xiàn)狀及發(fā)展趨勢[N];中國航空報;2012年

相關(guān)博士學位論文 前10條

1 張志勇;高潔凈度TiAl合金及其納米復(fù)合材料的制備，，組織和力學性能[D];北京科技大學;2015年

2 余龍;高鈮TiAl合金疲勞—蠕變交互作用研究[D];北京科技大學;2016年

3 舒世立;過渡族金屬元素和內(nèi)生陶瓷顆粒對TiAl壓縮性能的影響規(guī)律及機制[D];吉林大學;2013年

4 孫濤;原位自生Ti_2AlN/TiAl復(fù)合材料制備與高溫性能研究[D];哈爾濱工業(yè)大學;2012年

5 楊慧敏;TiAl-5Nb合金定向凝固過程中組織演化規(guī)律的研究[D];哈爾濱工業(yè)大學;2010年

6 廖翠姣;TiAl合金滲碳處理及其耐蝕性能研究[D];中南大學;2014年

7 羅江山;粉末冶金TiAl基合金的晶粒細化及其效應(yīng)研究[D];中國工程物理研究院;2014年

8 彭超群;循環(huán)熱處理對TiAl基合金組織與性能的影響[D];中南大學;2001年

9 昝祥;TiAl金屬間化合物高溫動態(tài)力學行為及變形機理研究[D];中國科學技術(shù)大學;2008年

10 袁勇;TiAl基金屬間化合物的脫溶反應(yīng)和位錯結(jié)構(gòu)研究[D];南京大學;2006年

相關(guān)碩士學位論文 前10條

1 邢發(fā)軍;TiAl/TiO_2界面相互作用的第一性原理研究[D];哈爾濱工業(yè)大學;2013年

2 王保棟;TiAl/Al_2O_3界面相互作用第一性原理研究[D];哈爾濱工業(yè)大學;2012年

3 韓波;殘留缺陷對鑄造TiAl合金擇優(yōu)取向?qū)悠�組織疲勞壽命的影響[D];昆明理工大學;2015年

4 李志明;基于Ti-Al-Nb-Cr-B體系的TiAl基合金設(shè)計與微觀組織研究[D];中國地質(zhì)大學(北京);2015年

5 王建成;區(qū)域加熱處理對TiAl合金組織演化的影響[D];南京理工大學;2015年

6 陳銳;準連續(xù)網(wǎng)狀Ti_5Si_3/TiAl基復(fù)合材料的高溫氧化行為研究[D];哈爾濱工業(yè)大學;2015年

7 王學菲;層狀結(jié)構(gòu)TiAl基復(fù)合材料合成機制與性能研究[D];哈爾濱工業(yè)大學;2015年

8 李明驁;B和C共同添加對TiAl基合金組織及性能影響研究[D];哈爾濱工業(yè)大學;2015年

9 劉浩;碳含量對TiAl合金凝固組織及性能的影響[D];哈爾濱工業(yè)大學;2015年

10 戴豪;TiAl_3對NaAlH_4吸放氫催化作用的影響因素及相關(guān)機制探究[D];廣西大學;2015年

本文編號：1690743