TiAl基金属间化合物的显微组织与断裂韧性

通过复合热机械处理新工艺，得到了细小均匀的ＴｉＡｌ基合金的显微组织，并研究了这些显微组织的断裂韧性。结果表明：全层片组织的断裂韧性最高，近层片组织的稍次，双态组织的最低。最后分析了ＴｉＡｌ基合金的显微组织被均匀细化的原因，并讨论了各种显微组织的断裂机制     

A MASSIVE TRANSFORMATION MECHANISM IN Ti-48Al ALLOY

ＡＭＡＳＳＩＶＥＴＲＡＮＳＦＯＲＭＡＴＩＯＮＭＥＣＨＡＮＩＳＭＩＮＴｉ－４８ＡｌＡＬＬＯＹ￥ＷｅｎＣｕｉｅ；ＬｉｎＪｉａｎｇｕｏ；ＣｈｅｎＣｈａｎｇｑｉ（ＤｅｐａｒｔｍｅｎｔｏｆＭａｔｅｒｉａｌｓＳｃｉｅｎｃｅａｎｄＥｎｇｉｎｅｅｒｉｎｇ，Ｂｅｉｊｉ...     

SUPERPLASTIC DEFORMATION OF TiAl BASED ALLOY

ＳＵＰＥＲＰＬＡＳＴＩＣＤＥＦＯＲＭＡＴＩＯＮＯＦＴｉＡｌＢＡＳＥＤＡＬＬＯＹ①ＺｈｏｕＫｅｃｈａｏ,ＨｕａｎｇＢａｉｙｕｎ,ＱｕＸｕａｎｈｕｉａｎｄＣｈｅｎｇＸｉａｏｑｕｎＮａｔｉｏｎａｌＫｅｙＬａｂｏｒａｔｏｒｙＦｏｒＰｏｗｄｅｒＭｅｔａｌｕｒｇ...     

预变形对Fe-Mn合金层错几率和阻尼性能的影响

探讨了Fe-Mn合金的高阻尼机制并采用G-L位错脱钉模型对其进行描述,同时通过测定层错几率,揭示了预变形(0-10%)对Re-Mn合金阻尼性能影响的本质.采用倒扭摆测试合金的阻尼性能,SEM和TEM观察显微组织,XRD测定物相体积分数和层错几率.结果表明,Fe-Mn合金的高阻尼性能来源于层错界面上Shockley不全位错的脱钉运动,实验结果很好地符合G-L位错脱钉模型;预变形量小于4%时,预变形处理虽然对合金的ε马氏体量没有太大影响,但明显增加了其层错几率,即Shockley不全位错的数量,合金的阻尼性能随变形量增加逐渐提高;预变形量大于4%时,由于ε马氏体和层错的相互交割,增大了Shockley不全位错的脱钉难度,所以合金的阻尼性能随变形量增加逐渐下降.     

A new sol-gel process for preparing Ba（Mg1／3Nb2／3）O3 nanopowders

The stacking fault energies of Ti-46Al-8.5Nb-0.2W alloy at 298 K and 1273 K were determined. The principle for the determination of the stacking fault energies is based on the fact that the stacking fault energy and the elastic interaction energy acting on the dissociated partial dislocations are equal. After the compress deformations with the strain of 0.2% at 298 K and 1273 K, and water quench to maintain the dislocation structures deformed at 1273 K, the dissociation distances between two partial dislocations were determined by weak beam transmission electron microscopy (WBTEM) technique. Based on these dissociation distances and the corresponding calculation method, the stacking fault energies were determined to be 77-81 mJ/m2 at 298 K and to be 57-60mJ/m2 at 1273 K respectively.     

Al-Mg合金中层错和孪晶形变能的第一性原理研究

通过基于密度泛函理论(DFT)的第一性原理计算了纯金属Al和Al Mg合金在(111)[112]滑移系的层错能和孪晶形变能,分析了Mg含量、占位对层错能和孪晶形变能的影响.计算选用了局域密度近似(LDA)和广义梯度近似(GGA PW91)2种近似方法,发现GGA PW91所获得的层错能与实验结果符合较好,研究结果表明,纯Al的层错能高于孪晶形变能,随着孪晶层厚度的增加孪晶形变能略有提高,6层呈完全镜面对称孪晶有的孪晶形变能最低:Mg含量增加使Al-Mg合金的层错能、变形孪晶形变能明湿降低;Mg在Al-Mg合金中占位对结合能和形成热的影响很小,当Mg处于层错层时略使层错能和孪晶形变能提高.     

XRD STUDY OF RECOVERY PROCESS OF COLD DEFORMED Ag AND Ag-Ce ALLOY

ＸＲＤＳＴＵＤＹＯＦＲＥＣＯＶＥＲＹＰＲＯＣＥＳＳＯＦＣＯＬＤＤＥＦＯＲＭＥＤＡｇＡＮＤＡｇ－ＣｅＡＬＬＯＹＮＩＮＧＹｕａｎｔａｏ;ＷＥＮＦｅｉ（ＫｕｎｍｉｎｇＩｎｓｔｉｔｕｔｅｏｆＰｒｅｃｉｏｕｓＭｅｔａｌｓＫｕｎｍｉｎｇ６５０２２１．Ｃｈｉｎａ）...     

CREEP BEHAVIOR OF AN EASY ORIENTED Ti-48Al PST CRYSTAL

ＣＲＥＥＰＢＥＨＡＶＩＯＲＯＦＡＮＥＡＳＹＯＲＩＥＮＴＥＤＴｉ－４８ＡｌＰＳＴＣＲＹＳＴＡＬ￥ＬｉｎＪｉａｎｇｕｏ；ＺｈｏｕＹａｊｉａｎ；ＺｈａｎｇＹｏｎｇｇａｎｇ；ＣｈｅｎＣｈａｎｇｑｉ（ＤｅｐａｒｔｍｅｎｔｏｆＭａｔｅｒｉａｌｓＳｃｉｅｎｃｅａｎ...     

Ta-7.5％W合金箔材冷轧过程中的位错结构演变

本文详细研究了Ta-7.5％W合金中取向为45°立方旋转织构{001}〈110〉方向的晶粒在冷轧变形过程中的位错结构和显微硬度演变规律.结果发现,当冷轧变形10％时,合金中形成了典型的bcc金属冷变形的位错结构,包括位错偶极子、位错反应形成的“剪刀”型位错以及位错碎片亚结构等;随着变形的进一步进行,其中一种晶粒中初期形...     

高密度电脉冲下材料微观结构的演变

几种粗晶材料经高密度电脉冲处理后，在材料内部形成了局域纳米结构，即冷轧α-Cu(Zn)中形成α—Cu(Zn)和β′-(CuZn)纳米相；低碳钢中形成纳米尺寸的奥氏体；TiC／Ni(Cr)金属陶瓷中形成纳米尺寸的定向TiC；LC6超硬铝中形成纳米尺寸的α-A1，粗晶纳米化转变的机制可归于电脉冲下多种因素的竞争，包括高速加热，热应力、削减的热力学势垒和较大的电子冲击力等。另外，电脉冲处理后的黄铜和金属陶瓷中分别形成了许多低能的位错组态、大量的层错和孪晶．这类缺陷结构演变与电脉冲输入的电能，热能和应力有关。     

STUDY OF RECOVERY IN DEFORMED Ni-Cr-Co SUPERALLOYS USING POSITRON ANNIHILATION

The recovery recrystallization of 3 deformed Ni-Cr-Co superalloys with different Co con-tents has been studied using positron annihilation technique and TEM.The alloys with lowCo content have more defects occurred than ones with high Co content,and the former maybe faster in dislocation recovery than the latter.Thus,the apparent activation energy ofrecrystallization increases with the increase of their Co content in alloys.The relationship be-tween apparent activation energy and stacking fault energy together with their effect on re-covery were also discussed.     

Microstructural characteristics of Ti-48Al-2Cr alloy

The microstructural characteristics of two-phase α ₂+γ titanium aluminide before and after deformation are investigated by transmission electron microscopy (TEM). The orientation relationships associated with the γ-γ combinations can be divided into three types: true twin, order domain, and pseudo-twin. Of the three orientation relationships, true twin accounts for more than 50%, which is most likely due to a minimization of interfacial energy related to misfit and interaction energy of interface atoms. During deformation, lamellar boundaries cause different resistance to the propagation of intersecting twin. Experimental observations and theoretical analysis consistently show that the resistance has the following sequence: F _120°<F _180°<F _60°<F _α2/γ .     

EFFECT OF MICROSTRUCTURES ON CYCLIC-OXIDATION BEHAVIOUR OF TiAl ALLOY

ＥＦＦＥＣＴＯＦＭＩＣＲＯＳＴＲＵＣＴＵＲＥＳＯＮＣＹＣＬＩＣ－ＯＸＩＤＡＴＩＯＮＢＥＨＡＶＩＯＵＲＯＦＴｉＡｌＡＬＬＯＹＺｈｏｕＫｅｃｈａｏ；ＨｕａｎｇＢａｉｙｕｎ；ＱｕＸｕａｎｈｕｉ；ＨｅＹｕｅｈｕｉ；ＫｏｎｇＧａｏｎｉｎｇ（ＰｏｗｄｅｒＭｅｔａ...     

ni—Cr—Co高温合金回复行为的正电子湮没研究

用正电子湮没技术及透射电镜研究了三种不同Co含量的 Ni-Cr-Co高温合金经室温形变后的回复再结晶过程.结果表明,在相同的形变量下,Co含量低的合金比 Co含量高的合金产生的缺陷多;在回复过程中,Co含量低的合金其位错回复比Co含量高的合金快,而且合金的表观再结晶激活能随Co含量的增加而增加.讨论了Co含量,表观再结晶激活能和层错能之间的关系以及它们对回复过程的影响。     

Ti—48Al合金片层组织的连续粗化机制

研究了 115 0℃时效时Ti 48Al合金全片层组织的连续粗化机制。片层组织的连续粗化不仅能通过片层界面缺陷 (如台阶、端部、弯曲的界面等 )迁移来实现 ,而且可以通过γ/γ片层界面迁移或分解的方式来实现 ;在真孪晶、伪孪晶和 12 0°旋转有序型γ/γ界面当中 ,12 0°旋转有序界面的稳定性最低 ,最容易迁移或分解 ;γ片层内的 12 0°旋转有序畴界与片层界面的交汇处易形成热沟(thermalgroove) ,它往往成为片层界面发生分解的起始部位     

Ti＋48Al＋B合金中硼化物的生长机理

研究了Ti-48Al (0.2～0.8)at%B合金中硼化物的生长机理。结果显示：合金中的硼化物均为C32结构的TiB2相;在加入0.2at%和0.5at%B的合金中只存在带状TiB2相;而加入0.8at%B的合金中除带状TiB2相外,还出现了少量六方形貌的块状TiB2相,块状硼化物是从液相中自由生长的初生TiB2相,其惯习面为（0001）基面和｛10∧-10｝柱面;而带状硼化物则是次生TiB2相,是通过L→β TiB2和L β→α TiB2反应与基体耦合生长的非规则共晶反应产物。两种形貌的TiB2颗粒均以台阶方式生长。     

INFLUENCE OF TWINNING AND DISLOCATION GLIDE DURING CREEP OF EQUIAXED AND LAMELLAR TiAl ALLOYS

１　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｃｒｅｅｐｒｅｓｉｓｔａｎｃｅｏｆｔｗｏｐｈａｓｅｔｉｔａｎｉｕｍａｌｕｍｉｎｉｄｅａｌｌｏｙｓｈａｓｂｅｅｎｃｏｎｆｉｒｍｅｄｔｏｄｅｐｅｎｄｎｏｔｏｎｌｙｏｎｌａｍｅｌｌａｒｖｏｌｕｍｅｆｒａｃｔｉｏｎｏｒｇｒａｉｎｓｉｚｅｂｕｔａｌｓｏｏｎｏｔｈｅｒｐａｒａｍｅｔｅｒｓｓｕｃｈａｓｔｈｅｍｏｒｐｈｏｌｏｇｙｏｆｅａｃｈｐｈａｓｅ［１－４］．Ｔｈｅｐｒｅｓｅｎｃｅｏｆｌａｍｅｌｌａｒｉｎｔｅｒｆａｃｅｓｌｅａｄｓｔｏｉｍｐｒｏｖｅｄｃｒｅｅｐｒｅｓｉｓ…     

STUDIES OF Nb–TiAl ALLOY BY POSITRON ANNIHILATION TECHNIQUES

利用正电子湮没寿命谱(PALS)和符合Doppler展宽(CDB)技术研究了Ti51Al49合金中Nb的掺杂效应.结果表明:低含量掺杂时,Nb原子主要偏聚在合金晶界处,提高了晶界位置的自由电子密度,有利于改善合金的室温韧性;而较高含量的Nb掺杂时,由于形成了新的晶体结构,合金基体及晶界处的自由电子密度减少,导致合金的脆性增加.     

STRUCTURE OF HYDRIDES IN HIGHLY HYDROGENATED Ti-6Al-4V ALLOY

The microstrueture and various hydrides precipitated in Ti-6A1-4V alloys containinghydrogen 0.16,0.58,0.87,1.49 wt-%,respectively,have been studied by means of TEM andX-ray diffraction.The Ti_3Al phase may precipitate when H over 0.58 wt-%.In the sametime,the morphology of hydrides gradually changed from rugged sheets to narrow laths asH contents increased.The microstructure of highly H-doped alloys is obviously fine.A mas-sive hydride and the hydride with tetragonal lattice were observed in the specimen containing1.49 wt-%H.The twin hydrides were found in the alloys with different H contents and theelectron diffraction patterns of the twin hydrides can be served as a simple criterion for distin-guishing the cubic and tetragonal structures.     

高锰钢爆炸硬化的微观机制SCIEI

选择压力峰值10—20GPa、脉冲宽度0.04—1.6μs等一系列脉冲载荷,利用轻气炮等模拟爆炸硬化过程,探索高锰钢爆炸硬化的微观机制,根据实验结果判断,激波作用后高锰钢中产生的大量孪晶是引起高锰钢爆炸硬化的主要原因。