溅射TiAlCr涂层对Ti-24Al-14Nb-3V抗氧化性能的影响

研究了溅射Ｔｉ５０Ａｌ１０Ｃｒ及Ｔｉ５０Ａｌ２０Ｃｒ涂层对Ｔｉ２４Ａｌ１４Ｎｂ３Ｖ抗高温氧化性能的影响。结果表明,在８００℃下,Ｔｉ５０Ａｌ１０Ｃｒ及Ｔｉ５０Ａｌ２０Ｃｒ涂层表面由于可形成粘附性良好的Ａｌ２Ｏ３膜,大大改善了Ｔｉ２４Ａｌ１４Ｎｂ３Ｖ的抗高温氧化性能。９００℃时在Ｔｉ５０Ａｌ１０Ｃｒ涂层表面长出大量ＴｉＯ２,导致其氧化增重较大;而在Ｔｉ５０Ａｌ２０Ｃｒ涂层表面生成了连续Ａｌ２Ｏ３,其抗氧化性能良好。然而,由于ＴｉＡｌＣｒ涂层与基体热膨胀系数不同,在循环氧化过程中涂层出现一些裂纹,导致其抗循环氧化性能有所下降。     

TiAlCr涂层对TiAl金属间化合物抗熔融硫酸盐热腐蚀的影响

研究了溅射ＴｉＡｌＣｒ 涂层对ＴｉＡｌ 金属间化合物抗硫酸盐热腐蚀性能的影响。结果表明,８５０ ℃时,９０ ％ Ｎａ２ＳＯ４ ＋ １０ ％ Ｋ２ＳＯ４ 中Ｔｉ５０Ａｌ 和Ｔｉ２４Ａｌ１４Ｎｂ３Ｖ 都遭受严重热腐蚀。ＴｉＡｌＣｒ 涂层能大大改善ＴｉＡｌ 金属间化合物的抗热腐蚀性能。带Ｔｉ５０Ａｌ１０Ｃｒ 涂层的Ｔｉ５０Ａｌ 表面形成一层完整致密的Ａｌ２Ｏ３ 膜, 涂层与基材之间无明显互扩散。带Ｔｉ５０Ａｌ１０Ｃｒ 涂层的Ｔｉ２４Ａｌ１４Ｎｂ３Ｖ 表面虽然也形成Ａｌ２Ｏ３ 膜, 但在其上面长出一些ＴｉＯ２ 瘤。这可能是涂层与基材之间的互扩散导致涂层中Ｔｉ 含量增加,Ａｌ 含量减少而生成ＴｉＯ２ 的结果。将涂层成分调整为Ｔｉ５０Ａｌ２０Ｃｒ 后, 带Ｔｉ５０Ａｌ２０Ｃｒ 涂层的Ｔｉ２４Ａｌ１４Ｎｂ３Ｖ 表面生成了连续的Ａｌ２Ｏ３ 膜, 其抗热腐蚀性能良好。     

Ti—Al系金属间化合物的氢脆机理

根据固体与分子经验电子理论发析计算了Ｔｉ－Ａｌ系金属化合物及含氢各相的价电子结构与解理能,结果表明：ＴｉｓＡｌ的氢脆是由于高氢含量下易生成δ脆性相引起的,而ＴｉＡｌ的氢脆是由于固溶氢减弱了含氢ＴｉＡｌ晶胞主干键并降低了解理能引起的,同时解释了一些尚有矛盾的实验结果,并提出了一些解决氢脆的实际方法。     

TiAlCr涂层对TiAl金属间化合物抗高温氧化性能的影响

研究了溅射Ｔｉ－５０Ａｌ－１０Ｃｒ涂层在８００－１０００℃对ＴｉＡｌ金属间化合物抗高温氧化性能的影响。结果表明,ＴｉＡｌ合金由于形成Ａｌ２Ｏ３和ＴｉＯ２的混合氧化物而表现出较差的抗高温氧化性能,而ＴｉＡｌＣｒ层由于形成粘附性了的Ａｌ２Ｏ３膜而大大提高了ＴｉＡｌ的恒温及循环氧化性能,经９００℃１０００ｈ长时间氧化。ＴｉＡｌＣｒ涂层对ＴｉＡｌ合金仍能提供很好的防护,涂层和基格结合我孔洞及裂纹出现,表现     

ISOTHERMAL SECTION OF PHASE DIAGRAM IN Ti-Al-Cr TERNARY SYSTEM AT 1000℃

应用多元扩散偶－电子探针微区分析技术及Ｘ射线衍射分析方法，测定了Ｔｉ－Ａｌ－Ｃｒ三元系相图１０００℃等温截面的含Ａｌ量达７５ａｔ．－％，含Ｃｒ量达７０ａｔ．－％的大部分区域。确定了Ｌｌ２结构的三元化合物相及其成分范围，完整地测定了ＴｉＡｌ，Ｔｉ３Ａｌ，ＴｉＡｌ２及ＴｉＡｌ３的相区范围及相平衡关系，明确了β－Ｔｉ相与ＴｉＣｒ２相的平衡关系及ＴｉＣｒ２相的成分范围     

Ti－Al－Cr三元系相图1000℃等温截面的研究

应用多元扩散偶－电子探针微区分析技术及Ｘ射线衍射分析方法，测定了Ｔｉ－Ａｌ－Ｃｒ三元系相图１０００℃等温截面的含Ａｌ量达７５ａｔ．－％，含Ｃｒ量达７０ａｔ．－％的大部分区域。确定了Ｌｌ２结构的三元化合物相及其成分范围，完整地测定了ＴｉＡｌ，Ｔｉ３Ａｌ，ＴｉＡｌ２及ＴｉＡｌ３的相区范围及相平衡关系，明确了β－Ｔｉ相与ＴｉＣｒ２相的平衡关系及ＴｉＣｒ２相的成分范围     

Ti－Al系金属间化合物价电子结构对其脆性的影响

根据余氏理论提出了一个价电子结构参数──脆性因子α，分析Ｔｉ－Ａｌ系金属间化合物的价电子结构并计算其α值，得到与实验规律一致的结果，从而解释了其脆性本质。     

Ti—Al系金属间化合物价电子结构对其脆性的影响

根据余氏理论提出了一个价电子结构参数－－脆性因子α，分析Ｔｉ－Ａｌ系金属间化合物的价电子结构并计算其α值，得到与实验规律一致的结果，从而解释了其脆性本质。     

Al3Ti基金属间化合物高能球磨亚稳转变的热力学分析

复相Ａｌ６７Ｍｎ８Ｔｉ２４Ｎｂ１有序金属产晔合物在高能球发生了无序化,并进一步非晶化,利用Ｍｉｅｄｅｍａ理论模型计算了合金呈有序金属间化合物,无序ｆｃｃ固溶体和非晶态的形成自由能,分析了球磨导致的缺陷能及其亚稳 的作用。     

复相Al3Ti基金属间化合物亚稳转变及重有序化

本文研究了Ａｌ６７ＭｎｓＴｉｗ２４Ｎｂ１复相金属间化合物在高能球磨过程中的亚稳态转变及亚稳粉末的加热时重有序化,由Ｌｌ２结构的基体和由ＤＯ２２型Ａｌ３（Ｔｉ,Ｎｂ）第二相组成的Ａｌ６７ＭｎｓＴｉ２４Ｎｂ１复相合金在球磨过程中,Ｌｌ２相有序度下降,ＤＯ２２相溶入,经１５ｈ后合金呈化学无序的ｆｃｃ过饱和固溶体,继续球磨则逐步转为成非晶态,其亚稳转变过程中的结构演变顺序为：Ｌｌ２＋ＤＯ２２→Ｌｌ２（弱有     

The effect of Ruthenium addition on the microstructure and mechanical properties of TiAl alloys

The high temperature compression behavior of TiAl–Ru alloys was studied at different temperatures and strain rates. Ru was found to have a strong strengthening effect on TiAl alloys. However the Ru addition amount was limited by its low solubility in γ-TiAl and α₂-Ti₃Al, and the detrimental effect of excessive ternary phase precipitation. Furthermore, the melting temperature decreases when Ru ≥0.6 at.% as the alloy composition approaches a ternary eutectic point. The strengthening mechanism is discussed and two separate mechanisms are proposed, viz. solid solution strengthening and refined colony strengthening. Intergranular cracks were found in the alloys with low Ru or no Ru addition, but were barely detected as Ru content increased to above 0.6 at.%. It was suggested that Ru showed a beneficial effect on both strength and ductility of TiAl alloys due to the refined colony size. Three-point bend test results showed that the Ru addition can also improve the room temperature ductility of TiAl alloys. Hot workability was increased according to the compression tests. Thermal-mechanically treated TiAl–Ru had much smaller grain size than the heat-treated samples due to dynamic recrystallization. But it did not show superior strength in the compression test compared to the heat-treated samples. The Zener–Hollomon parameter was calculated from the compression strength of heat-treated TiAl–Ru alloys. Its relationship with dynamic recrystallization and hot work is discussed. The mechanical properties of TiAl–Ru alloys are compared with TiAl–Nb samples and demonstrate a promising combination of strength and ductility.     

Influence of Fe substitutions on the deformation behavior and fault energies of Ni3Ge–Fe3Ge L12 intermetallic alloys

Ni₃Ge exhibits a yield strength anomaly, whereas the yield strength of Fe₃Ge shows a normal decline with temperature, and there is a gradual transition from anomalous to normal behavior as Fe content increases. A dramatic strengthening for 77 K deformation has also been noted to occur in these alloys as a result of increasing Fe content. The combined use of transmission electron microscopy (TEM) and image simulations has facilitated identification of the operative deformation mechanisms and allowed for a quantitative measure of superdislocation dissociations. A transition from octahedral glide and Kear–Wilsdorf locking to cube glide of superdislocations has been observed to coincide with an increase in either deformation temperature or Fe content. The low-temperature strengthening has been correlated with enhanced cross-slip, which is aided by a significant lowering of the cube-plane antiphase boundary energy with increasing Fe content. It is proposed that the strengthening and the transition to cube glide are promoted by an increase in the complex stacking fault energy, which enhances both cross-slip and cube-plane mobility.     

TiAl-X三元金属间化合物的价电子结构分析

应用固体与分子经验电子理论分析了Ti-48Al-2X(X=Nb，Cr，V，Mn，W)(at％)三元合金的价电子结构，其结果可以为研究TiAl基合金的宏观性能提供理论参考.     

Microstructure characterization and tensile properties of β phase containing TiAl pancake

The microstructure and tensile properties of Ti-44Al-6V-3Nb-0.3Y (at.%) alloy after canned forging were investigated. SEM results showed that the TiAl pancake exhibits inhomogeneous microstructure, which can be ascribed to the temperature drop and friction between billet and outer pack during forging, as well as the intrinsic anisotropy of lamellar colony. By means of TEM observation and EBSD analysis, the microstructure in the dominant area of the pancake was further characterized. This deformation area consists of 87.7% content of γ grains plus some refined lamellar colonies and the rest of B2 grains. The grain size ranges between 1 μm and 8.5 μm. High-angle boundaries dominate the deformation microstructure, several substructures and twins are observed as well. Additionally, current forged alloy exhibits excellent high temperature tensile strength and noteworthy yield stress anomaly (YSA), with ultimate tensile strength 680 MPa and yield strength 620 MPa at room temperature, increasing to 850 MPa and 750 MPa at 700 °C, respectively. The anomalous strengthening of current TiAl alloy is temperature dependent and can be interpreted by the dislocation cross-slip pinning mechanism.     

On the possibility of the self-blocking of dislocations in various materials

Experiments on heating without stress after a preliminary plastic deformation of bcc metals (armco Fe, Mo) have been carried out. The temperatures of deformation and heating were varied in wide limits. No transformations of dislocations from a curvilinear into a rectilinear blocked form were observed; i.e., no self-blocking of dislocations has been found in these bcc metals, in contrast to the previously investigated intermetallic compounds of the Ni₃Al and TiAl type. A comparison of the behavior of dislocations in the bcc metals with that of single dislocations in TiAl has been performed. Using a previously suggested model, times that characterize the formation of kinks and their moving apart from one another have been introduced. It is shown that the change in the relationships between these times controls the changes in the shape of dislocations both during plastic deformation and upon heating in the absence of an external load. An analysis of the totality of experimental data obtained leads to a conclusion that it is the multivalley nature of the potential relief that plays the determining role in blocking and self-blocking of dislocations. Since the potential relief in bcc metals is single-valley, neither self-blocking of dislocations nor anomalous behavior of the yield stress has been observed. The problem of what equilibrium structures of the single-dislocation core in TiAl correspond to shallow and deep valleys and, also, what is the barrier that must be overcome for the passage between them, has also been considered.     

氧化锆基固体电解质价电子结构研究

应用固体与分子经验电子理论（EET理论）计算了不同Y2O3掺杂量的ZrO2基固体电解质材料价电子结构,探讨了成分、价电子结构与离子电导率间的关系,得到了与实验规律一致的结果。提出了可用复合参量P来预测离子电导率,为从理论上预测具有高离子导电性的YSZ材料成分提供依据。     

Ti—56Al单晶的形变位错结构及反常屈服机制的研究

应用TEM对Ti-56Al单昌[103]有序畴区位错结构进行研究,并提出修正的钆轧－解钉模型以解释1／2＜110]普通位划不是长而直的纯螺位错及位错碎片不是沿纯螺方向排列等实验现象和反常屈服机制。认为,当TiAl合金中的Al含量较低时,1／2＜110]普通位划控制的反常屈服行为可用Viguier的钉扎－解钉模型解释;当TiAl合金名的Al含量较高时,1／2＜110]普通位划控制的反常屈服行为可用本文提出的修正的钉扎－解钉模型解释。     

Rotating strength of forged TiAl alloys

In order to evaluate the rotating strength of TiAl alloys, mechanical and rotating burst testing were conducted on wrought TiAl having various microstructures. The rotating burst strength of the nearly lamellar (NL) structure was greater than near gamma (NG) or fully lamellar (FL) structures. The mechanical properties which have an affect on the rotating strength were yield strength and elongation, and only a slight amount of elongation allows the rotating burst characteristics of TiAl alloys to change from ceramic-like maximum stress dependency to metal-like mean stress dependency. It was estimated that forged NL–TiAl has greater rotating strength above 1000 K than superalloys in current use.