全层片组织TiAl基合金室温断裂机理的研究

在ＳＥＭ和ＴＥＭ下对Ｔｉ３３Ａｌ３Ｃｒ０．５Ｍｏ合金全层片组织薄板状和薄膜状试样分别进行了动态拉伸，并原位观察了试样中形核及扩展过程，发现裂纹遇到内相界面时会履发生偏转或裂尖发生钝化；主裂纹妈使剪切带断裂而与微裂纹相连接的方式扩展并沿曲折路径进行。     

超塑性变形TiAl基合金中的孔洞

研究了超塑性Ｔｉ－３３Ａｌ－３Ｃｒ－０．５Ｍｏ（质量分数,％）合金中孔洞的形成和发展过程及其与合金的断裂之间的关系,研究结果表明 ,ＴｉＡｌ基合金在超塑性变形过程中产生的孔洞有３种类型,它们分别形成于三叉晶界外、晶界上和晶粒内。三叉晶界上的孔洞一般呈Ｖ型,而晶界和晶内的孔洞则呈圆形或椭圆,分析认为,孔洞的长大、扩展和聚集是造成ＴｉＡｌ基合金超塑性拉伸断裂的主要原因。     

TiAl基合金热机械处理新工艺技术的研究

探讨了包套锻复合热机械处理新工艺技术对（Ｔｉ－３３Ａｌ－３％Ｃｒ）－０．５＾Ｍｏ合金显微组织，变形亚结构和室温、高温力学性能的影响。试验结果表明，经过包套锻复合热机械处理，可以在ＴｉＡｌ基合金整个试样上获得均匀，细小的各种典型形态的显微组织。     

冷却速度对锻造TiAl基合金组织演变的影响

利用光学显微镜,研究了冷却速度对锻造Ｔｉ－４８Ａｌ－２Ｃｒ组织演变的影响。结果表明：冷却速度主要影响锻造ＴｉＡｌ基合金焦产物的形貌,而对晶团尺寸的影响较小,锻造ＴｉＡｌ基合金在α相转变温度θα以上等温热处理后,采用炉冷、空冷、油冷和水冷、会依次转变为全层状组织、层状组织加魏氏体组织、块状转变组织加魏氏体组织、块状转变组织加羽毛状组织。     

用循环热处理细化铸造TiAl基合金的显微组织

设计了一种新的循环热处理工艺，并用正交设计试验研究了各热处理工艺参数，即加热速度、保温温度、保温时间、冷却速度和循环数物铸造ＴｉＡｌ基合金显微合组织和显微硬度（ＨＶ５）的影响，结果表明：循环热处理工艺均能不同程度地提高显微度，提高了最大最大幅度在客因素的影响在小排列依次为加速速度，保温时间、保温温度、冷却速度、循环次数，利用循环热处理获得不同类型的显微组织，在正交基础上确定了优化的热处理工艺，并用     

加热速度对TiAl基合金显微组织的影响

利用Gleeble-1500热模拟机研究了加热速度对铸态TiAl基合金显微组织的影响，提出了在相界外形成层片组织的物理模型，结果表明，5次快速加热循环处理可将TiAl基合金晶粒细胞化至50μm以下；单次快速加热可破坏TiAl基合金层片组织的稳定性，使层片组织破碎，快速加热条件下的重结晶形核以晶界形核为主，并可在相界发生。     

TiAl基合金断裂情况的研究现状及发展趋势

对TiAl基合金断裂情况的研究现状进行了论述。从显微结构的控制提高其断裂韧性及其它性能，加载率、温度和环境对TiAl基合金的断裂及韧化机理的影响，变形和断裂行为，韧化机理和断裂机理的研究情况等五个方面对前人的工作进行了分析与比较，有助于对TiAl合金的变形为断裂，断裂过程及其韧化机理更进一步的理解。同时进一步提出了TiAl基合金的断裂模型是什么，传统的COD法能否合理地测试TiAl合金的断裂韧性，用什么方法才能更好地评定此类合金的断裂韧性等需解决的问题，并对TiAl基合金发展趋势进行了初步的探讨。     

液晶显示器用高分子取向层及其取向机理

在液晶显示器中，低分子量液晶材料在经过摩擦处理的高分子取向层作用下，能够发生取向。这种高分子取向层对于制造具有优良光电特性的液晶器件是十分重要的。在大多数场合下，所采用的薄膜状高分子取向层是由聚酰亚胺类材料制成的，因为它们具有优良的耐热性、粘附性、加工性和取向效应。本文对液晶显示用聚酰亚胺高分子材料及其当前流行的取向机理进行了综述介绍，并提出了自己的一些看法。     

TiAl基合金双态组织试样室温断裂的研究

采用预制缺口试样，测试了Ｔｉ－３３％Ａｌ－３％Ｃｒ－０．５％Ｍｏ合金双态组织材料的室温ＫＩＣ值。使用扫描电子显微镜，研究了薄板状试样内裂纹扩展动态过程，并采用透射电子显微镜，进一步研究了薄膜试样内裂纹扩展动态过程，以及裂纹尖端附近区域上的变形亚结构。     

Effects of microstructures on the deformation and fracture behaviors of TiAl-based alloys

The fracture toughnessK _Ic, the tensile deformation and fracture behaviors of different microstructures ofγ-TiAl based alloy, Ti-33Al-3Cr-0.5Mo] were studied at room temperature. It is found that theK _Ic value is lower in the duplex microstructure, and increases with the increase of vol pct of the lamellar microstructure, and that the full lamellar has the highestK _Ic value. Cleavage was the dominant fracture mechanism in the duplex microstructure material. In contrast, for the full lamellar microstructure the high anisotropy of deformation and the large strain discontinuity at grain boundaries resulting in decohesion of grain boundaries are the main fracture processes. Project supported by the National Natural Science Foundation of China and National Advanced Materials Committee of China Synopsis of the first author Chen Xiaoqun, associated professor, born in Jan. 1965, current research fields: physical metallurgy of high-temperature structural intermetallic compounds.     

Microstructure evolution of Ti-47Al-2Cr-2Nb alloy in the liquid-metal-cooling (LMC) directional-solidification process

The microstructure evolution of Ti-47Al-2Cr-2Nb alloy was investigated on liquid metal cooling type directional solidified apparatus at high temperature gradient.The analysis shows that it is solidified with primary β cells/dendrites,and then α phase is formed through peritectic reaction.Once the columnar grains grow into the steady state,the lamellar orientation inclined with the angle of 45° to the withdrawal direction is more favored than that with parallel to the withdrawal direction.In addition,α phase...     

Microstructure and mechanical properties of Al_3Ti-based alloys in Al-Ti-Mo-X quaternary systems

A part of Al-Ti-Mo-Cr quaternary phase diagram is constructed for the microstructure control of D022-Al3Ti or its derivative, L12-(Al,Cr)3Ti, -based alloys. It was found that quaternary bcc phase equilibrates with either D022-Al3Ti or L12-(Al,Cr)3Ti, or both, exist in large compositional areas. The mechanical properties is strongly affected by precipitates appearing, and presumably alloy microstructures.     

Effect of Lamellar Orientation on Crack Paths in PST Crystals of -TiAl Based Alloys

The effect of lamellar orientation on crack paths in PST crystals of -TiAl based alloys was investigated by in-situ SEM technique. The results indicate that the crack paths in PST crystals of -TiAl based alloys are strongly dependent on lamellar orientation of PST crystals, and the differently oriented PST crystals show different nucleation and propagation mechanisms of crack, resulting in different levels of fracture toughness.     

层片状堆焊材料的研制

为了研制一种柔性比较好的层片状堆焊材料,用来修复易磨损的零件表面和小型的管材类零件等,选择有机硅密封胶、聚乙烯醇、环氧树脂、水玻璃为粘结剂,与硬质材料Ni60H进行混合,做成层片状堆焊材料;另外再加入WC(碳化钨)作为硬质相,利用TIG焊在Q235钢基体上进行堆焊.结果表明:以有机硅密封胶、有机硅密封胶与环氧树脂1∶1为粘结剂的堆焊材料具有良好的柔韧性,可以任意弯折.以有机硅密封胶与环氧树脂1∶1为粘结剂的堆焊材料加入WC和CaF2后的焊接组织均匀、无缺陷,且堆焊层具有良好的耐磨性能,其洛氏硬度值为HRC43.83.     

Ni－Ti合金中基体柱状晶的取向分布规律

柱状晶的生长都具有一定的取向,形状记忆效应与柱状晶的生长取向有着非常直接的关系。我们利用Ｘ射线衍射仪可测出Ｎｉ－Ｔｉ合金柱状晶生长取向「１００」Ｂ２随着衍射角θ＾′的变化规律,从而对利用和推广形状记忆合金有着极为现实的意义。     

Alignment of primary Al<Subscript>3</Subscript>Ni phases in hypereutectic Al-Ni alloys with various compositions under high magnetic fields

Al-Ni hypereutectic alloys with various compositions were solidified under various magnetic field con- ditions to investigate the alignment of primary Al3Ni phases. The results showed that the application of high magnetic fields could improve the homogeneity of the primary Al3Ni phase distribution and induce the alignment of primary Al3Ni phases in the direction perpendicular to the magnetic field direction to form chain-like structures. However, the alignment was different from the orientation of the Al3Ni...     

Ti40阻燃钛合金的基础研究

利用XRD、OM、TEM等方法研究了Ti40合金吸氢与放氢后的组织演变规律。研究表明：由于氢在β相中的溶解度很高,Ti40合金中并没有发现氢化物的析出,但β晶界处更加宽化;当氢含量较高时,β相内开始析出α相,并伴随着硅化物粒子的析出;吸氢Ti40合金放氢后,合金中的相与原始合金一致。     

Texture of deformed Cu-Cr-Zr alloys

The influences of plastic deformation, aging treatment, and alloying elements on the texture of Cu-Cr-Zr alloys were explored. The texture component and intensity of Cu-Cr-Zr alloys under various working conditions after aging treatment were characterized using the orientation distributing function (ODF). The influence of Zr content on the texture of Cu-Cr-Zr alloys was also analyzed. The reduction pass and deformation level were primary factors influencing the texture. Rolling texture appeared in a rolled plate and the fibrous textures of {111} and {001} were detected after 80% deformation. Fibrous texture with a main constituent of {111} improved the tensile strength of the alloy wire. The texture contents of {110}<331> and {110}<112> were predominated, whereas, those of {113}<332> and {112}<111> were in the minority in the Cu-Cr-Zr alloy with a higher Zr content (>0.5wt%). However, in the samples with a lower Zr content (<0.1wt%), the texture contents of {113}<332>, {112}<111>, and {111}<110> were in the majority.     

NiTi（X）合金中第二相与R相关系研究

研究了NiTi(X)合金中第二相与R相变的关系问题,结果表明：如果合金中第二相与基体存在的共格关系,且在[111]B2方向存在优先拉应力场,NiTi(X)合金中的R相变即可发生,否则只能诱发马氏体相变。