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Investigation on creep mechanism of a Ni3Al-based Single Crystal Superalloy IC6SX under 760℃/540MPa

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Investigation on Creep Mechanism of a Ni3Al-based Single Cry...

Microstructure evolution,mechanical properties and creep mechanisms of Mg-12Gd-1MM-0.6Zr(wt%)magnesium alloy

中国材料大会2012

作者： Liwu Jiang Shusuo Li Meiling Wu National Center for Materials Service Safety University of Science and Technology Beijing School of Materials Science and Engineering Beijing University of Aeronautics and Astronautics

ISBN: (纸本)9783037856086;3037856084

The creep behaviors of a Ni3Al-base single crystal superalloy IC6SX prepared by spiral grain selection method was studied systematically under the testing condition of 760℃/540MPa. The microstructure evolution, movement of dislocations, formation of the dislocation networks and dislocation configuration during the creep process were investigated by scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. The results showed that the creep performance of the single crystal alloy IC6SX is excellent under 760℃/540MPa. The experimental results showed that the creep curve of the Ni3Al-base single crystal superalloy IC6SX was divided into three stages, including decelerating creep stage, steady-state creep stage and accelerated creep stage. The microstructure and the dislocation configuration were different at different stage during the creep and the raft microstructure has not been formed. The creep mechanism was main slipping characterized by dislocation glide mechanism.

关键词： Ni3Al Single crystal superalloy creep mechanism Dislocation configuration IC6SX

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Journal of Rare Earths 2021年第5期39卷 600-608页

作者： Bibo Li Kui Zhang Guoliang Shi Kaikun Wang Yongjun Li Xinggang Li Minglong Ma Jiawei Yuan State Key Laboratory of Nonferrous Metals and Process GRINM Group Co.Ltd.(GRINM)Beijing 100088China School of Materials Science and Engineering University of Science and Technology BeijingBeijing 100083China GRIMAT Engineering Institute Co. Ltd.Beijing 101407China General Research Institute for Nonferrous Metals Beijing 100088China

In this research,the microstructure evolution,mechanical properties,and creep mechanisms of Mg-12 Gd-1 MM-0.6 Zr(wt%)alloy under different conditions were systematically studied using scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-ray diffraction(XRD),and tensile creep *** the microstructure of the as-cast sample,the average grain size is about 42μm,and the eutectic compounds were determined to be Mg_(5)(Gd_(0.8)MM_(0.2)).During homogenization,these eutectic compounds gradually dissolve,and Mg_(12)MM particles are *** hot extrusion,complete dynamic recrystallization(DRX)occurs,resulting in equiaxial grains with an average grain size of about 12μm and the formation of streamlines consisting of Mg_(12)MM particles along the extrusion direction(ED).After T5 treatment(225℃for 7 h),a large number ofβ'(Mg_(7)Gd)phases are precipitated on the{11-20}αhabit plane and are interconnected,forming an interlaced network *** ultimate tensile strength(R_(m)=405 MPa)and yield strength(R_(P0.2)=288 MPa)of the T5 sample are significantly higher than those of the as-extruded sample(R_(m)=289 MPa,R_(P0.2)=185 MPa),but the elongation(A=4%)was remarkably lower than that of the as-extruded sample(A=18%).When crept at225℃under 100 MPa,the steady-state creep rates of the as-cast,as-extruded,and T5 samples are1.59×10^(-8),1.08×10^(-8),and 1.40×10^(-8)s^(-1),respectively,and their total strains within 100 h are respectively breaking,0.81%,and 0.92%,indicating that the as-extruded alloy exhibits the best creep *** analysis reveals that,during the creep process of the T5 sample,theβ'particles coarsen and the precipitate-free zones(PFZs)widen,which increase the steady-state creep rate and the total strain within 100 h as compared with the as-extruded sample.

关键词： Magnesium alloy Extrusion creep mechanism Microstructure evolution Precipitation Rare earths

High temperature creep mechanisms of a single crystal superalloy: A phasefield simulation and microstructure characterization

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Progress in Natural Science:Materials International 2020年第3期30卷 366-370页

作者： Ronghai Wu Yunsong Zhao Yanfei Liu Xing Ai School of Mechanics Civil Engineering and Architecture Northwestern Polytechnical University Beijing Institute of Aeronautical Materials AECC Sichuan Gas Turbine Establishment AECC Hunan Aviation Power Plant Research Institute

The high temperature creep behavior of a single crystal Ni-based superalloy was studied by combined experimental and numerical methods. The creep test results showed that the creep curves exhibited a three-stage feature. The qualitative explanations for each stage of the creep curves were carried out based on the microstructure characterizations of γ/γ′ phases and dislocations. An elastoplasticity incorporated phase-field model was developed to provide quantitative understanding on directional coarsening(rafting) of γ′ phase. The simulation results showed that the directionality of γ′ coarsening was induced by both dislocation activity in γchannels and elastic inhomogeneity between γ and γ’ phases, therein the dislocation activity played a major *** findings provide new insights into the design of novel single crystal superalloys with improved creep properties.

关键词： creep mechanism Dislocation activity Phase-field method Single crystal superalloy

Understanding the creep behaviors and mechanisms of Mg-Gd-Zn alloys via machine learning

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Journal of Magnesium and Alloys 2024年第8期12卷 3281-3291页

作者： Shuxia Ouyang Xiaobing Hu Qingfeng Wu Jeong Ah Lee Jae Heung Lee Chenjin Zhang Chunhui Wang Hyoung Seop Kim Guangyu Yang Wanqi Jie Graduate Institute of Ferrous and Eco Materials Technology(GIFT) Pohang University of Science and Technology(POSTECH)Pohang 37673Republic of Korea State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an 710072China Xi’an Rare Metal Materials lnstitute Co.Ltd Xi’an 710016China Department of Materials Science and Engineering Pohang University of Science and Technology(POSTECH)Pohang 37673Republic of Korea DepartmentAdvanced Institute for Materials Research(WPI-AIMR) Tohoku UniversitySendai 980-8577Japan Institute for Convergence Research and Education in Advanced Technology Yonsei UniversitySeoul 03722South Korea

Mg-Gd-Zn based alloys have better creep resistance than other Mg alloys and attract more attention at elevated ***,the multiple alloying elements and various heat treatment conditions,combined with complex microstructural evolution during creep tests,bring great challenges in understanding and predicting creep *** this study,we proposed to predict the creep properties and reveal the creep mechanisms of Mg-Gd-Zn based alloys by machine *** the one hand,the minimum creep rates were effectively predicted by using a support vector regression *** complex and nonmonotonic effects of test temperature,test stress,alloying elements,and heat treatment conditions on the creep properties were *** the other hand,the creep stress exponents and creep activation energies were calculated by machine learning to analyze the variation of creep mechanisms,based on which the constitutive equations of Mg-Gd-Zn based alloys were *** study introduces an efficient method to comprehend creep behaviors through machine learning,offering valuable insights for the future design and selection of Mg alloys.

关键词： Mg-Gd-Zn based alloys Machine learning creep rate creep mechanism Constitutive equation

Through-thickness heterogeneity in creep properties of friction stir welding 7B50-T7451 aluminum alloy thick plate joint:Experiments and modeling

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Chinese Journal of Aeronautics 2023年第6期36卷 378-389页

作者： Huan WANG Weifeng XU Hongjian LU Shaanxi Key Laboratory of Friction Welding Technologies Northwestern Polytechnical UniversityXi'an 710072China

Through-thickness heterogeneity in creep properties of 7B50-T7451 aluminum alloy Friction Stir Welding(FSW)joints was *** tests for three slices of the FSW joint were conducted at the temperature of 150-200℃ and applied stress of 60-225 *** theta projection method was used to predict creep curves and minimum creep *** results show that the minimum creep rate increases and creep rupture life decreases with the increase of creep temperature and applied *** properties of the FSW joint deteriorate along the thickness direction from the top to the *** threshold stress of all three slices of the FSW joint decreases with the increase of creep temperature and even disappears at 200℃ for the bottom *** activation energy approaches the activation energy of the lattice self-diffusion of *** value of true stress exponent for different slices is approximately equal to *** predominant creep mechanism of the FSW joint is dislocation viscous glide by lattice *** is more,a constitutive model is established based on the theta method to accurately describe creep behavior ofdifferent slices of the FSW joint.

关键词： 7B50 high strength aluminum alloy creep mechanism creep modeling Friction stir welding Theta projection method Through-thickness heterogeneity

Microstructure and creep properties of Mg-4Al-2Sn-1(Ca,Sr) alloys

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Transactions of Nonferrous Metals Society of China 2010年第7期20卷 1184-1191页

作者： B.H.KIM K.C.PARK Y.H.PARK I.M.PARK Department of Material Science and Engineering Pusan National UniversitySan 30 Jangjeon-dongGeumjeong-guBusan 609-735Korea

The effects of Ca and Sr addition on the microstructure and creep properties of Mg-4Al-2Sn alloys were examined. Tensile tests at 25 ℃ and 200 ℃ and creep tests at 150 ℃ and 200 ℃ were carried out to estimate the room temperature and high temperature mechanical properties of these alloys. The microstrueture of the Mg-4Al-2Sn alloy showed dendritic a-Mg, Mg17Al12 and Mg2Sn phases. The latter two phases precipitated along the grain boundaries. The addition of Ca and Sr resulted in the formation of ternary CaMgSn and SrMgSn phases within the grain. The grain size was reduced slightly with the addition of Sr and Ca. The tensile strength was decreased by the addition of Ca and Sr at room temperature. However, the high temperature tensile strength was increased. The creep strength was improved by the addition of Ca and Sr.

关键词： magnesium alloys Ca Sr void initiation mechanical properties creep mechanism

Elucidating the role of precipitated phase particles in modifying creep properties of as-cast Mg-Bi/Sn-based alloys

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Journal of Magnesium and Alloys 2024年第11期12卷 4682-4693页

作者： Gang Xu Wei-li Cheng Yi-hao Luo Hui Yu Li-fei Wang Hang Li Hong-xia Wang Jin-hui Wang School of Materials Science and Engineering Taiyuan University of TechnologyTaiyuan 030024China b School of Materials Science and Engineering Hebei University of TechnologyTianjin 300132China Qinghai Provincial Key Laboratory of New Light Alloys Qinghai Provincial Engineering Research Center of High Performance Light Metal Alloys and FormingQinghai UniversityXining 810016China School of Materials Science and Engineering Zhejiang UniversityHangzhou 310000China

The study developed the three alloy systems with different precipitates and examined the role of precipitated phase particles in modifying the creep properties of as-cast Mg^(-1)0Bi-0.5Mn-0.5Ag(BMQ1000),Mg-5Bi-5Sn-0.5Mn-0.5Ag(BTMQ5500)and Mg^(-1)0Sn-0.5Mn-0.5Ag(TMQ1000)alloys at temperatures ranging from 423 to 473 K and stresses of 45-85 *** values of n for the BMQ1000,BTMQ5500,and TMQ1000 alloys were determined as 6.67,5.75,and 5.92,***,the activation energy for these alloys was found to be 164.71,134.68,and 135.93 k J/mol,*** results suggested that the creep properties followed the order of BTMQ5500>TMQ1000>BMQ1000.A coarse and uneven distribution of the Mg_(3)Bi_(2)precipitated phase in the BMQ1000 alloy leads to a feeble pining effect on dislocation slipping and generates substantial stress *** TMQ1000 alloy,while the nanoscale Mg_(2)Sn precipitates have a stronger barrier effect on dislocations than the Mg_(3)Bi_(2)in the BMQ1000 alloy,their ability to inhibit dislocation climbing is comparatively ***,it was found that Mg_(2)Sn precipitates andα-Mg exhibited a preferential orientation relationship of(020)Mg_(2)Sn//(-1010)Mg,and the morphology of the precipitated phase transformed in a way that hinders dislocation movement *** addition,elastic interactions between the precipitated phases are *** above-mentioned factors are largely responsible for the notable enhancement in creep ***,it is ascertained that cross-slip and pyramidal(c+a)slip are primary creep mechanisms in the BMQ1000 *** contrast,the dominant mechanisms in TMQ1000 and BTMQ5500 alloys are dislocation climb and pyramidal(c+a)***,stacking faults(SFs)and twinning assist in the creep deformation of the BTMQ5500 alloy.

关键词： Magnesium alloy Microstructural characteristics creep properties Precipitates creep mechanism

High-temperature creep properties of uranium dioxide pellet

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Transactions of Nonferrous Metals Society of China 2010年第2期20卷 238-242页

作者：高家诚王良芬王勇吴曙芳 College of Materials Science and Engineering Chongqing University

High-temperature creep properties of sintered uranium dioxide pellets with two grain sizes （9.0 μm and 23.8μm） were studied. The results indicate that the creep rate becomes a little faster with the reduction of the uranium dioxide grain size at the same temperature and the same load. At the same temperature, the logarithmic value of the steady creep rate vs stress has linear relation, and with increasing load, the steady creep rate of the sintered uranium dioxide pellet increases. Under the same load, the steady creep rate of the sintered uranium dioxide pellet increases with increasing temperature; and the creep rates of sintered uranium dioxide pellet with the grain size of 9.0 μm and 23.8 μm under 10 MPa are almost the same. The creep process is controlled both by Nabarro--Herring creep and Hamper-Dorn creep for uranium dioxide pellet with grain size of 9.0 μm, while Hamper---Dora creep is the dominantmechanism for uranium dioxide with grain size of 23.8 μm.

关键词： uranium dioxide pellet grain size creep property creep mechanism

Microstructure heterogeneity and creep damage of DZ125 nickel-based superalloy

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Progress in Natural Science:Materials International 2014年第3期24卷 266-273页

作者： Haofang Sun Sugui Tian Ning Tian Huichen Yu Xianlin Meng School of Materials Science and Engineering Shenyang University of Technology Beijing Institute of Aeronautical Materials

The creep behavior of the DZ125 superalloy at high temperatures has been investigated based on the creep properties measurement and microstructure observations. The experimental results show that, after full heat treatment, the fine and coarser cuboidal γ0precipitates distributed in the dendrite arm and inter-dendrite regions, respectively, the boundaries with various configurations located in the inter-dendrite regions. In the primary creep stage, the cuboidal γ0phase in the alloy transformed into the rafted structure along the direction vertical to the stress *** dislocations slipping and climbing over the rafted γ0phase are attributed the deformation mechanism of the alloy during steady-state ***(1/2)?1 1 0? dislocations slipping in the γ matrix and ?1 1 0? super-dislocations shearing into the γ0phase are the deformation mechanisms of the alloy in the latter stage of creep. And then the alternate slipping of dislocations results in the initiation and propagation of the micro-cracks along the boundaries until the occurrence of the creep fracture. Since the grain boundaries with various angles relative to the stress axis distribute in the different regions, the initiation and propagation of micro-cracks along the boundaries display the various features.& 2014 Chinese Materials Research Society. Production and hosting by Elsevier B.V. All rights reserved.

关键词： DZ125 nickel-based superalloy Microstructure creep mechanism