ELECTRONIC STRUCTURE OF γ′-PHASE IN SUPERALLOY CONTAINING Mg AND W

本文用实空间格林函数递推方法,计算了含杂质Mg,W的γ′-Ni_3Al相的电子结构,结果表明,Mg和W原子进入γ′相后都失去部分外层电子,使得原子半径减小,从而有利于杂质以替代方式进入γ′相;Mg和W原子同时进入γ′相,使Mg与γ′基体之间的相互作用增强,有利于γ′相产生稳定结构。     

QUANTITATIVE DETERMINATION OF NETWORK γ'-PHASE IN Ni-BASE SUPERALLOY CONTAINING HIGH Al AND Ti

<正> 铸造镍基高温合金如M17G,M17,M17E中Al+Ti含量分别为9.65,9.90及10.10,其γ′相含量也较高。合金的高温强度在很大程度上取决于γ′相的数量,所以准确地测定γ′相含量是值得重视的。通常采用电解提取的方法,在过钝化溶解的条件下使基体充分溶解,定量地保留γ′相来测定其含量。但由于Al,Ti含量提高,γ′相含量增加,经过较高温度、较长时间的时效,在电解提取γ′相时,虽然基体溶解掉,但γ′相却常常牢固地附着在样品表面上,不     

PLASTIC DEFORMATION AND DISLOCATION STRUCTURE IN γ'-PHASE OF A DIRECTIONALLY SOLIDIFIED Ni-BASE SUPERALLOY

The dislocation structure of directionally solidified(DS)Rene 80 superalloy during tensileand creep deformation has been studied by TEM.In tensile deformation,γ'shearing occurs byslip of APB-coupled(1/2)<110>dislocation pairs on{111}planes at temperatures below760℃.and by slip of SISF-seperated(1/3)<112>superpartials which have dissociated on{111}planes into a(1/2)<110>screw superpartial and a(1/6)<112>edgesuperpartial with an APB in between at temperatures equal to or above 760℃.In creepdeformation,γ'shearing occurs again by slip of SISF-seperated(1/3)<112>superpartialswhich have not dissociated on{111}planes and by diffusive slip of APB-coupled(1/2)<110>dislocation pairs at 760℃,618 MPa.However,no γ'shearing occurs at 980℃,190MPa.During secondary creep at 760℃,618 MPa or at 980℃,190 MPa,2-dimensional net-works have formed at γ/γ'interfaces,and the strain is mainly the result of diffusion control-led climb of dislocation networks at γ/γ'interfaces.The dependence of secondary creep rate εupon size a and volume fraction v_■ of cubic γ' has been found to be ■∝α/v_f~(2/3).     

PLASTIC DEFORMATION AND DISLOCATION STRUCTURE IN γ'-PHASE OF A DIRECTIONALLY SOLIDIFIED Ni-BASE SUPERALLOY

本文利用透射电镜观察了定向凝固高温合金DS Rene80在拉伸及蠕变时的位错亚结构。试验结果表明:在低于760℃拉伸时,切割γ′粒子的是在{111}面上夹有APB的(1/2)〈110〉位错对。在不低于760℃拉伸时,切割γ′粒子的是在{111}面上夹有超点阵内禀层错(SISF)γ(1/3)〈112〉不全位错;这些不全位错在大应力的作用下于{111}面上将分解为一根(1/2)〈110〉螺位错和一根(1/6)〈112〉刃位错,并在其间夹有一个APB。在760℃,618MPa条件下蠕变时,切割γ′粒子的是在{111}面上夹有SISF的(1/3)〈112〉不全位错;这些不全位错此时不分解。与此同时,亦有(1/2)〈110〉位错对切割γ粒子。在980℃,190MPa条件下蠕变时,则无γ′粒子被切割的现象。在760℃,618MPa及980℃,190MPa条件下蠕变至第二阶段时,在γ/γ′界面上都形成了二维位错网络墙,墙上位错的攀移是合金形变的控制因素。第二阶段蠕变速率(ε)与立方γ′粒子的尺寸(α)和体积分数(V_f)的关系符合ε∝α/V_f~(2/3)     

EFFECT OF Nb ON γ'-PHASE PRECIPITATIONHARDENED Ni-Cr-Al-Ti BASE SUPERALLOY

本文研究了Nb在γ′相沉淀强化型Ni-Cr-Al-Ti系高温合金中的作用。结果指出:适量的Nb不但能提高该合金的室温和高温强度,而且还能提高室温和高温塑性,Nb主要通过强化γ′相而使合金强度提高,通过细化晶粒而使台金塑性改善。     

TRANSFORMATION KINETICS AND COARSENING OF LAMELLAR STRUCTURE IN γ-TiAl ALLOY

研究了Ｔｉ－４７．８ａｔ．－％Ａｌ合金从α相区冷至室温再在双相区时效后，层状组织的转变机理及不连续粗化．层状组织转变过程与时效温度和形成过饱和α＿２单相时的冷却速度有关．建立了层状组织转变的动力学模型．层状组织的稳定性随片间距减小而降低，表现为时效时发生不连续粗化．     

DIRECTIONAL COARSENING OF THE γ'-PHASE DURING COMPRESSION CREEP OF A SINGLE CRVSTAL NICKEL-BASE SUPERALLOY

对「００１」取向单晶镍基合金恒温恒载压缩蠕变不同时间的组织形貌进行了ＳＥＭ和ＴＥＭ观察表明：蠕变初期,两立方γ‘相沿平行于应力轴方向扩散相连定向生长成为条形筏结构;垂直通道中基体「００１」晶向共格应变量减小,应变能降低是合金元素定向扩散形成γ’相符结构的驱动力;压缩与拉伸蠕变相比较,γ’相形筏所需要的时间较长,应力较大。     

INFLUENCE OF ASSOCIATED AND SEPARATE PRECIPITATION OF γ″ AND γ′ ON STRUCTURE STABILITY IN INCONEL718 AND MODIFIED ALLOYS

The precipitation behavior in Inconel 718 and modified alloys has been studied by means ofTEM.The structure of associated precipitation and compact morphology of γ″+γ′ were ob-tained by modifying the contents of Al,Ti and Nb.Experimental results show that the com-pact morphology of γ″+γ′ has the best structure stability at higher temperatures.Instead ofthe transformation γ″→δ in alloy 718 the dissolution of strengthening phases in modified alloyleads material degradation.     

PHASE INTERFACE SEGREGATION OF Mg IN A Ni-BASE SUPERALLOY IN100

The segregation of Mg to phase interfaces in a nickel base superalloy IN 100 has been investi-gated using EPT(Electron Microprobe Technique).AES(Auger Electron Spectroscopy)and EDS analyses on thin TEM film.The results show that Mg segregates to the phase inter-faces of MC/γ and γ′/γ.The segregation concentration and layer thickness of Mg onMC/γ phase interface are larger than that on γ′/γ phase interface.Mg is not only a grainboundary segregation element,but also a phase interface segregation one.     

ELECTRONIC STRUCTURE OF Pd-Y-Si GLASSES

The electronic structure of Pd-Y-Si glass has been investigated by ESCA and quantum chem-ical calculation.It was found that the valence electrons of Y transferred to Si atoms in thismetallic glass,forming polar covalent bonds.Perhaps these strong covalent bonds link Si andY atoms to form clusters that hinder the process of crystallization.     

FORMATION AND ROTATION OF γ' RAFTS IN Ni-BASE SINGLE CRYSTAL SUPERALLOY NASA IR100

研究了ＮＡＳＡＩＲ１００单晶在高温持久变形中γ′筏形组织的形成及其在缩颈区内的转动，发现γ′沉淀在持久变形初期即沿着垂直于拉伸应力轴的方向相互连结，变形大约５０ｈ后形成了完善的γ′筏形组织，对拉断试样的纵截面进行了扫描电镜观察，发现缩颈区内的γ′筏形组织不再垂直于应力轴，而是绕着应力轴转动，初步提出了γ′筏形组织的形成及转动机理。     

MORPHOLOGY OF ION-NITRIDED LAYER AND STRUCTURE OF γ'/ε INTERFACES

使用电子显微镜研究了５５０℃，６ｈ离子渗氮的３５ＣｒＭｏ钢渗层的组织形貌和界面结构．结果表明，渗层外层为分层相间分布的ε＋γ′条带状组织。在化合物内层的γ′相中有空位盘、位错、层错四面体和孪晶．ε相和γ′相之间的界面光滑且平直．除了观察到一个原子层结构台阶，也发现多个原子层高度的结构台阶．大量晶体缺陷的存在是加速离子渗氮过程的主要原因。     

DIRECTIONAL COARSENING OF γ'PRECIPITATES IN A SINGLE CRYSTAL NICKEL BASE SUPERALLOY

研究了［００１］取向单晶高温合金ＣＭＳＸ—４在１２５３Ｋ，３５０ＭＰａ拉伸蠕变中γ＇沉淀沿垂直于外应力轴方向的粗化过程及其机理。发现在定向粗化期间立方形γ＇沉淀的边缘部分优先生长，γ—γ＇界面呈内凹形方式推进，进而封闭了与之相邻的垂直基体通道（平行于［００１］）；相互连接的γ＇沉淀逐渐消耗并最终耗尽被封闭的残余垂直通道而发展成完整的筏形组织。定向粗化导致了γ＇沉淀沿［００１］方向的尺寸逐渐减小，水平基体通道（垂直于［００１］）的宽度大幅度增加。对γ＇沉淀的特殊生长方式和两共格相形貌的演变特征进行了分析与讨论。     

NUMERICAL SIMULATION OF TURBULENCE AND ITS STRUCTURE IN A HYDROCYCLONE

１ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｓｔｒｕｃｔｕｒｅｏｆｔｕｒｂｕｌｅｎｃｅｉｎｈｙｄｒｏｃｙｃｌｏｎｅｓｈａｓａｎｉｎｆｌｕｅｎｃｅｎｏｔｏｎｌｙｏｎｔｈｅｓｅｐａｒａｔｉｏｎｐｅｒｆｏｒｍａｎｃｅｂｕｔａｌｓｏｏｎｔｈｅｅｎｅｒｇｙｃｏｎｓｕｍｐ...     

PSEUDO-DENDRITE GROWTH CHARACTERISTICS OF γ′PRECIPITATES IN SINGLE CRYSTAL NICKEL BASE SUPERALLOY

镍基单晶高温合金经充分均匀化、高温固溶和直接按时效处理后，沉淀出一种类树枝晶形态γ′相．类树枝晶γ′相的析出温度（Ｔ_（ｓγ′））敏感于局部合金成分，它的形核密度（Ｉ）与过冷度（△Ｔ_（γ′））成指数关系：Ｉ（μｍ~（－２））＝２．５×１０~（－３）ｅｘｐ（０，１１△Ｔ_（γ′））．在较小过冷度，类树枝晶γ′相尺寸与直接时效时间成正比．它的择优生长方向是〈１１０〉，与基体取向相同，完全共格．类树枝晶γ′的形核机制包括扩散和非扩散两种，并趋向对称形核．     

A PAT STUDY OF INFLUENCES OF PRECIPITATION ON DEFECTS AND ELECTRONIC DENSITY IN Al-Li-Cu-Mg-Zr ALLOYS

ＡＰＡＴＳＴＵＤＹＯＦＩＮＦＬＵＥＮＣＥＳＯＦＰＲＥＣＩＰＩＴＡＴＩＯＮＯＮＤＥＦＥＣＴＳＡＮＤＥＬＥＣＴＲＯＮＩＣＤＥＮＳＩＴＹＩＮＡｌＬｉＣｕＭｇＺｒＡＬＬＯＹＳ①ＷｕＷｅｉｍｉｎｇ，ＧａｏＹｉｎｇｊｕｎ，ＬｕｏＬｉｘｉｏｎｇ，ＤｅｎｇＷ...     

PROCESS OF ELECTRONIC LOCALIZATION IN DISORDERED SYSTEM

１ＩＮＴＲＯＤＵＣＴＩＯＮＡｓｉｓｗｅｌｋｎｏｗｎ，ｎｏｎｉｎｔｅｒａｃｔｉｏｎｅｌｅｃｔｒｏｎｓｉｎｄｉｓｏｒｄｅｒｅｄｓｙｓｔｅｍａｒｅｌｏｃａｌｉｚｅｄ．Ｓｉｎｃｅ１９５８Ａｎｄｅｒｓｏｎ［１］ｆｉｒｓｔｐｏｉｎｔｅｄｏｕｔｔｈｅｐｏｓｓｉｂｉ...     

TEM STUDIES OF THE W PHASE AND ITS ORDERED W'PHASE IN RARE EARTH Mg ALLOYS

By means of transmission electron microscopy(TEM),the W phase and its ordered W'phase in as-cast Mg-Zn-Zr-Y system alloys were studied.The W phase,which distributes alongthe grain boundaries in the form of a lamellar eutectoid with Mg,is of FCC structure with α=0.865 nm.The W'phase,which is an ordered structure of the W phase with α=2.055 nm,was found in the alloy with lower Y content.The W and W'phases have a simple orientationrelationship of(100)_W//(100)_(W'),(010)_W//(010)_(W'),and(001)_W//(001)_W;but they do nothave an orientation relationship with the α-Mg matrix.The results of convergent electroncliffractions(CBD)on these phases show that their point group is m3m and that the space group isFm3m.     

PHASE COMPOSITION AND TRANSFORMATION STRESS OF PRIMARY LAMELLAR STRUCTURE IN γ-TiAl-BASED DUPLEX ALLOY DURING ISOTHERMAL DECOMPOSITION

应用Ｘ射线衍射测定了过饱和α２单相的Ｔｉ－４５％Ａｌ合金在９５０℃等温分解过程中,初生片层形成时的γ相转变分数及２和γ相晶格参数的变化。结果表明,初生片层中α２和γ相晶格参数的变化,结果表明,初生片层中α２相是亚稳相,其成分可以由自由能成分曲线的亚稳态α２相与γ相自由能成分曲线公切线的切点稳定,该成分的确定对定量计算合金自由能及发生不连续粗化的转变驱动有十分重要的作用;     

EFFECT OF VOLUME FRACTION AND SIZE OF FINE γ' ON CREEP STRENGTH OF A DS NICKEL-BASE SUPERALLOY

本文研究了定向凝固K3镍基高温合金的蠕变强度与细小γ′粒子的数置和尺寸的关系。实验结果证明,随着固溶温度升高,铸态粗大γ′逐步溶解并在随后冷却过程重新析出均匀细小正方形的γ′粒子。细小γ′体积分数(v_f)和尺寸(α)都随固溶温度的升高而增大,当固溶温度从1100℃升至1230℃,v_f从0.25增至0.63,α从0.10μm增至0.32μm。随着固溶温度的升高,第二阶段蠕变速率降低,持久寿命延长,大幅度提高合金的蠕变性能。适当的高温固溶加时效处理(如1210—1230℃,4h+900℃,32h)可提高定向凝固合金的中温(760℃,73.8kgf/mm~2)持久寿命10倍左右。 合金的中温蠕变性能取决于细小γ′的体积分数(v_f),尺寸(α)及其间距(λ),在固定温度和应力下,第二阶段蠕变速率((?))与它们之间符合以下关系。 (?)∝ λ~2/α或(?)∝ α/v_f~(2/3)(1-v_f~(1/3))~2 用透射电镜观察了合金三个蠕变阶段位错亚结构的变化,据此提出蠕变的位错模型和合金的强化机制,并导出第二阶段蠕变速率与γ′体积分数、尺寸和间距之间的关系式,与实验结果完全符合。