MICROSTRUCTURAL STABILITY OF LAMELLAR TiAl BASED ALLOYS AT HIGH TEMPERATURES

１　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｌａｍｅｌｌａｒｍｉｃｒｏｓｔｒｕｃｔｕｒｅｅｘｈｉｂｉｔｓｂｅｔｔｅｒｍｅｃｈａｎｉｃａｌｐｒｏｐｅｒｔｉｅｓｔｈａｎｔｈｅｓｉｎｇｌｅγｐｈａｓｅｏｒｄｕｐｌｅｘｓｔｒｕｃｔｕｒｅｉｎＴｉＡｌｂａｓｅａｌｌｏｙ［１］．Ｉｎｅｑｕｉｌｉｂｒｉｕｍ,γ（ＴｉＡｌ）ａｎｄα２（Ｔｉ３Ａｌ）ｐｌａｔｅｓｉｎｔｈｅｌａｍｅｌｌａｒｍｉｃｒｏｓｔｒｕｃｔｕｒｅｈａｖｅｔｈｅｆｏｌｌｏｗｉｎｇｏｒｉｅｎｔａｔｉｏｎｒｅｌａｔｉｏｎｓｈｉｐ：｛１１１｝γ∥｛０００１…     

SUPERPLASTIC BEHAVIOR OF HOT-FORGED TiAl-BASED ALLOY

１ＩＮＴＲＯＤＵＣＴＩＯＮＴｉＡｌｂａｓｅｄａｌｏｙｓａｒｅｃｏｎｓｉｄｅｒｅｄｔｈｅｍｏｓｔｆａｖｏｒａｂｌｅｃａｎｄｉｄａｔｅｓａｓａｄｖａｎｃｅｄｓｔｒｕｃｔｕｒａｌｍａｔｅｒｉａｌｓｆｏｒａｅｒｏｓｐａｃｅａｐｐｌｉｃａｔｉｏｎｂｅｃａｕ...     

DUCTILITY ENHANCEMENT OF Al RICH Ni 3Al BY DIRECTIONAL SOLIDIFICATION

１　ＩＮＴＲＯＤＵＣＴＩＯＮＡｌｒｉｃｈＮｉ３Ａｌ（ｓｔｏｉｃｈｉｏｍｅｔｒｉｃａｎｄｈｙｐｅｒｓｔｏｉｃｈｉｏｍｅｔｒｉｃ）ｉｓｓｕｐｅｒｉｏｒｔｏＮｉｒｉｃｈＮｉ３Ａｌａｓａｈｉｇｈｔｅｍｐｅｒａｔｕｒｅｍａｔｅｒｉａｌ．ＩｔｉｓｃｏｎｓｉｄｅｒａｂｌｙｓｔｒｏｎｇｅｒｔｈａｎＮｉｒｉｃｈＮｉ３Ａｌａｔｈｉｇｈｔｅｍｐｅｒａｔｕｒｅ［１］．Ｉｎａｄｄｉｔｉｏｎ,ＡｌｒｉｃｈＮｉ３ＡｌｉｓｍｏｒｅｒｅｓｉｓｔａｎｔｔｏｏｘｉｄａｔｉｏｎｔｈａｎＮｉｒｉｃｈＮｉ３Ａｌｂｅｃａｕｓ…     

Continuous recrystallization in pure Al 1.3% Mn investigated by local orientation analysis

１　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｃｌａｓｓｉｃａｌｗｏｒｋｓｏｎｃｏｎｔｉｎｕｏｕｓｒｅｃｒｙｓｔａｌｌｉｚａｔｉｏｎ（ｏｒｒｅｃｒｙｓｔａｌｌｉｚａｔｉｏｎｉｎｓｉｔｕｏｒｅｘｔｅｎｄｅｄｒｅｃｏｖｅｒｙ）ａｒｅｔｈｏｓｅｏｆＨｏｒｎｂｏｇｅｎａｎｄＫ¨ｏｓｔｅｒ［１～３］ｏｎＡｌＦｅａｎｄＡｌＣｕ．ＩｔｉｓｔａｋｅｎｆｏｒｇｒａｎｔｅｄｔｈａｔｔｈｅＺｅｎｅｒｐｉｎｎｉｎｇｄｕｅｔｏｓｅｃｏｎｄａｒｙｐｒｅｃｉｐｉｔａｔｉｏｎｉｓｔｈｅｍａｉｎｒｅａｓｏｎｆｏｒｔｈｅｏｃｃｕｒｒｅ…     

THERMAL ACTIVATION ANALYSIS ON STRAIN RATE DEPENDENCE OF HIGH TEMPERATURE TENSILE PROPERTIES IN TiAl ALLOY

１　ＩＮＴＲＯＤＵＣＴＩＯＮＴｗｏｐｈａｓｅγｔｉｔａｎｉｕｍａｌｕｍｉｎｄｅｓ,ｏｒＴｉＡｌａｌｌｏｙｓ,ｕｓｕａｌｌｙｃｏｍｐｏｓｅｄｏｆａｍａｊｏｒｐｈａｓｅｏｆγＴｉＡｌａｎｄａｍｉｎｏｒｐｈａｓｅｏｆα２Ｔｉ３Ａｌ,ａｒｅｅｍｅｒｇｉｎｇａｓｐｏｔｅｎｔｉａｌｈｉｇｈｔｅｍｐｅｒａｔｕｒｅｓｔｒｕｃｔｕｒａｌｍａｔｅｒｉａｌｓｂｅｃａｕｓｅｏｆｔｈｅｉｒｈｉｇｈｅｌｅｖａｔｅｄｔｅｍｐｅｒａｔｕｒｅｓｔｒｅｎｇｔｈ,ｌｏｗｄｅｎｓｉｔｙａｎｄｅｘｃｅｌｌｅｎｔｏｘｉｄａｔ…     

THERMAL ACTIVATION ANALYSIS ON TENSILE DEFORMATION IN Ti47Al2Mn2Nb ALLOY

１　ＩＮＴＲＯＤＵＣＴＩＯＮγＴｉＡｌ／α２Ｔｉ３ＡｌｔｗｏｐｈａｓｅｉｎｔｅｒｍｅｔａｌｌｉｃｓｏｒＴｉＡｌａｌｌｏｙｈａｓｒｅｃｅｎｔｌｙｒｅｃｅｉｖｅｄｉｎｃｒｅａｓｉｎｇａｔｔｅｎｔｉｏｎｂｅｃａｕｓｅｏｆｉｔｓｐｏｔｅｎｔｉａｌａｓａｓｔｒｕｃｔｕｒａｌｍａｔｅｒｉａｌｆｏｒｈｉｇｈｔｅｍｐｅｒａｔｕｒｅａｐｐｌｉｃａｔｉｏｎｓ,ｗｈｉｃｈａｒｉｓｅｓｆｒｏｍｉｔｓｅｌｅｖａｔｅｄｈｉｇｈｔｅｍｐｅｒａｔｕｒｅｓｔｒｅｎｇｔｈ,ｌｏｗｄｅｎｓｉｔｙａｎｄｇｏｏｄｏｘｉｄａｔｉｏ…     

Ti_2Al PHASE IN AlRICH TiAl INTER METALLICS

１　ＩＮＴＲＯＤＵＣＴＩＯＮＡｆｔｅｒＬｏｉｓｅａｕａｎｄＬａｓａｌｍｏｎｉｃｆｏｕｎｄａＴｉ２ＡｌｐｈａｓｅｉｎｔｈｅＡｌｒｉｃｈＴｉＡｌｉｎｔｅｒｍｅｔａｌｌｉｃｓ［１］,ｗｅａｌｓｏｉｄｅｎｔｉｆｉｅｄｉｔｉｎｔｈｅａｎｎｅａｌｅｄｉｎｔｅｒｍｅｔａｌｌｉｃｗｉｔｈｃｏｍｐｏｓｉｔｉｏｎｏｆＴｉ４８．３Ａｌ５１．７［２］．ＴｈｅＴｉ２Ａｌｐｈａｓｅｗａｓａｈｅｘａｇｏｎａｌｓｔｒｕｃｔｕｒｅｗｉｔｈｌａｔｔｉｃｅｐａｒａｍｅｔｅｒｓａ＝０．３０１ｎｍａｎｄｃ＝１．４３１ｎｍ．Ｋａｕｆ…     

DISLOCATION DISSOCIATIONS AND FAULT ENERGIES IN Ni 3Al ALLOYS DOPED WITH PALLADIUM

１　ＩＮＴＲＯＤＵＣＴＩＯＮＩｔｉｓｗｅｌｌｋｎｏｗｎｔｈａｔｔｈｅｙｉｅｌｄｓｔｒｅｎｇｔｈｏｆｏｒｄｅｒｅｄＮｉ３ＡｌａｌｌｏｙｓｗｉｔｈＬ１２ｓｔｒｕｃｔｕｒｅｉｎｃｒｅａｓｅｓａｎｏｍａｌｏｕｓｌｙｗｉｔｈｉｎｃｒｅａｓｉｎｇｔｅｍｐｅｒａｔｕｒｅ．Ｔｈｕｓ,ｔｈｅＮｉ３Ａｌａｌｌｏｙｓｈａｖｅｂｅｅｎｅｘｔｅｎｓｉｖｅｌｙｉｎｖｅｓｔｉｇａｔｅｄｄｕｒｉｎｇｔｈｅｐａｓｔｄｅｃａｄｅｓｄｕｅｔｏｔｈｅｉｒｐｏｔｅｎｔｉａｌｈｉｇｈｔｅｍｐｅｒａｔｕｒｅａｐｐｌｉｃａｔｉｏｎｓ．Ｈｏ…     

Effect of trace Sc and Zr on aging behavior and tensile properties of 2618 alloy

１　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅａｌｕｍｉｎｕｍａｎｄａｌｕｍｉｎｕｍａｌｌｏｙｓａｄｄｅｄｔｒａｃｅｓｃａｎｄｉｕｍｈａｖｅｇｒｅａｔｉｍｐｒｏｖｅｍｅｎｔｉｎｍｅｃｈａｎｉｃａｌｐｒｏｐｅｒｔｉｅｓ,ｔｈｅｒｍａｌｓｔａｂｉｌｉｔｙ,ｗｅｌｄｂｉｌｉｔｙｅｔｃ［１］．ＳｃａｎｄｉｕｍｉｓｃｏｎｓｉｄｅｒｅｄｔｏｂｅａｈｏｐｅｆｕｌｔｒａｃｅｅｌｅｍｅｎｔｔｏｄｅｖｅｌｏｐａｄｖａｎｃｅｄｗｒｏｕｇｈｔａｌｕｍｉｎｕｍａｌｌｏｙｄｕｅｔｏａｄｉｓｐｅｒｓｅｄｐｈａｓｅＡｌ３Ｓｃｐｒｅｃ…     

DYNAMIC MECHANICAL BEHAVIOR OF Fe 3Al UNDER TENSILE IMPACT

１　ＩＮＴＲＯＤＵＣＴＩＯＮＳｏｍｅｏｆｔｈｅｏｒｄｅｒｅｄｉｎｔｅｒｍｅｔａｌｌｉｃｓ,ｅｓｐｅｃｉａｌｌｙｔｈｏｓｅｂａｓｅｄｏｎａｌｕｍｉｎｉｄｅｓ,ｓｕｃｈａｓＦｅ３Ａｌ,ｐｏｓｓｅｓｓｍａｎｙａｔｔｒａｃｔｉｖｅｐｒｏｐｅｒｔｉｅｓｆｏｒｓｔｒｕｃｔｕｒａｌｕｓｅａｔｅｌｅｖａｔｅｄｔｅｍｐｅｒａｔｕｒｅｓｉｎｈａｒｓｈｅｎｖｉｒｏｎｍｅｎｔｓ［１－３］．Ｉｎｇｅｎｅｒａｌ,ｔｈｅａｌｕｍｉｎｉｄｅｓｃｏｎｔａｉｎｓｕｆｆｉｃｉｅｎｔａｍｏｕｎｔｓｏｆａｌｕｍｉｎｉｕｍｔｏｆｏｒｍ…     

复相Al3Ti—8Mn基合金的显微组织

在Ａｌ－Ｔｉ－Ｎｂ－８Ｍｎ四元系邻近Ｌ１２型Ａｌ３Ｔｉ－８Ｍｎ成份区合金中,随Ｎｂ含量变化,其显微组织发生明显变化。通过对不同合金的微观组织的考察,进一步确认了在Ａｌ６７Ｍｎ８Ｔｉ２５基金中加Ｎｂ并相应调整Ａｌ和Ｔｉ含量可形成ＤＯ２２型Ａｌ３（Ｔｉ,Ｎｂ）,Ｌ１０型ＴｉＡｌ和Ｇａ２Ｈｆ型Ａｌ２Ｔｉ３种类型的第二相。本文列举了Ａｌ６７Ｍｎ８ｔＩ２３Ｎｂ２,Ａｌ６５Ｍｎ８Ｔｉ２６－５Ｎｂ０．５,Ａｌ５     

添加Nb对LI2型Al3Ti—8Mn基合金的相组成影响

在单相Ll2结构Al67Mn8Ti25金属间化合物中加入少量Nb（0．5at％～4．0at％）,并相应调整Al,Ti含量后,其组织变化显著。在邻近Al－Ti－Nb-8Mn四元系Al3Ti－8Mn区域设计了32种实验合金,随Nb加入量的变化,其结构除单相Ll2外,尚有Ll2＋A12Ti,L12＋DO22,LI2＋LI0,Ll2＋Al2Ti＋DO22和Ll2＋Al2Ti＋Ll0等5种复相或多相组织。Nb含量一定,随Al／Ti比的降低,会导致片状或网纹状Al2Ti组织析出,Nb含量较高时会进一步促使波纹或针片状Ll0TiAl相的形成。初步制定了Al－Ti－Nb-8Mn四元系邻近Al3Ti-8Mn区域的室温相组成图。     

不同结构及成分的Al3Ti合金成键特征的分析

利用Ｘ射线光电子能谱法分析了Ａｌ３Ｔｉ系合金的成键性质。Ｄ０２２型Ａｌ３Ｔｉ成键性质的各向异性有利于稳定Ｄ０２２结构，Ｌｌ２型Ａｌ３Ｔｉ成键方式呈各向同性。Ａｌ６７Ｔｉ２５Ｍｎ８合金中Ａｌ－Ｔｉ键与Ａｌ６７Ｔｉ２５Ｎｉ８合金相比具有球化程度高，方向性小的特点，有利于提高塑性。     

Sn替代Si和B对Ti50Ni22Cu18Al4Si4B2合金机械研磨非晶化的促进作用

采用Xn替代Ti50Ni22Cu18Al4Si4B2合金中的Si和B1形成Ti50Ni22Cu18Al4Snx(Si0．67B0．33)6-x(x=0，3，6)系列合金．所有的预制合金碎屑经过机械研磨均发生非晶化转变．随着合金中Sn含量的增加，球磨产物中转变未尽的晶体相α-Ti含量减少．由Sn完全替代Si和B的Ti50Ni22Cu18Al4Sn6合金，机械研磨可形成与熔体急冷几乎相同的单一均匀非晶相，过冷液态温度区间可达到66K．     

The influence of thermal processing route on the microstructure of some TiAl-based alloys

The influence of a range of different continuous cooling rates from the alpha phase field has been investigated in large-grain-sized (∼1500 μm) Ti48Al2Cr2Nb and in grain-refined Ti48Al2Cr2Nb1B alloys. In addition the microstructure of direct laser-fabricated samples of Ti48Al2Nb2Mn has been examined in order to assess the influence of the complex heating cycle and high cooling rate on this alloy. It has been found that the critical cooling rates to obtain a particular structure are higher in grain-refined Ti48Al2Cr2Nb1B than in the alloy without boron (B). The increase in the amount of the lamellar structure during cooling takes place in different manners in the two alloys. The formation of the lamellar structure in laser-treated samples has been found to be very different with the formation of Al-rich gamma regions separating regions with a lamellar structure. The possible factors affecting phase transformations are discussed in terms of the role of grain boundaries and B in solution in the solid state transformations and, in the case of the laser-treated samples, of melting and remelting.     

Microstructure and tensile properties of orthorhombic Ti–Al–Nb–Ta alloys

Microstructure and tensile properties of orthorhombic Ti–Al–Nb–Ta alloys have been studied. In order to optimize ductility and strength of the orthorhombic alloys with the nominal compositions of Ti–22Al–23Nb–3Ta and Ti–22Al–20Nb–7Ta, various thermomechanical processing steps were implemented as part of the processing route. With a special heat treatment before rolling to obtain a fine and homogeneous rolled microstructure, the rolled microstructure resulted in a good combination of high tensile yield strength and good ductility of the alloys through available solution and age treatments. The duplex microstructure with equiaxed α₂/O particles and fine O phase laths in a B2 matrix, deforming in α₂+B2+O phase field and treating in O+B2 phase field, possesses the highest tensile properties. The R.T. yield strength and ductility of the Ti–22Al–20Nb–7Ta alloy are 1200 MPa, and 9.8% respectively. The yield strength and ductility values of 970 MPa and 14% were also maintained at elevated temperature (650°C).     

Strength and fracture of two hot-rolled Ti–Al–Si–Nb dual phase alloys based on Ti3Al

Ti–Al–Si–Nb dual phase alloys are mainly composed of α₂-Ti₃Al matrix and Ti₅Si₃ silicide phases. In this paper, two alloys (402 and 405) whose Si contents are 2 and 5 at% respectively were arc melted and hot-rolled into sheets with different amounts of deformation. The silicide phase (Ti,Nb)₅(Si,Al)₃ was broken up into small pieces and redistributed in the α₂ matrix during the hot-rolling. Improved strength and ductility of the two alloys were observed after hot-rolling, which can be attributed to both the finely distributed reinforcement silicide phase and refinement of the matrix grain size. The mechanical properties of the two alloys are dependent on their volume fractions of the silicide phase: the strength of alloy 405 is higher than that of alloy 402, while alloy 402 is more ductile than alloy 405. The brittle–ductile transition temperature of the two dual phase alloys is between 600 and 800°C. The surface slip on the dual phase alloys was also observed. Obvious separation between the (Ti,Nb)₅(Si,Al)₃ particles and the α₂ matrix is found on the fracture surfaces obtained at high temperature, showing dimple-like morphology.     

快速凝固Al—Zr—Ti合金的组织结构

利用透射电子显微镜研究了快速凝固Al-4Zr-2Ti(原子百分比）合金的组织结构。结果表明：快凝合金的显微硬度与其显微组织密切相关,快凝合金急冷态组织显示出单一相-过饱和Al基固溶体,此时显微硬度为220HV,快凝合金经420℃退火4h ,具有立方结构的亚稳相L12-Al3(Zr、Ti)析出,此时显微硬度达到峰值260HV,而经420℃退火20h,则L12相转为为DO23相,同时,显微硬度下降到150Hv。     

A STUDY ON ALUMINIDE COATINGS ON TiAl ALLOYS BY PACK CEMENTATION METHOD

1. IntroductionIntermetallic compound TiAl is expected to be one of the candidates for high temperature systems such as aircraft engines because it has a high specific strength at elevatedtemperatures[1,2]. However, there are two major drawbacks with intermetallic compoundTiAl as an engineering material: one is its poor room temperature ductility and the otheris the poor oxidation resistance above 800xi. The former has been generally overcomeby modification of the microstructure using ternar…     

钛的电阻钎焊技术研究

研究了Ｔｉ－２４Ａｌ－１１Ｎｂ－２Ｓｉ和Ｔｉ－２４Ａｌ－１１Ｎｂ－５Ｓｉ金属间化合物合金的热轧组织与性能,结果发现：随着变形量的增加,两种合金第二相Ｔｉ５Ｓｉ３变得细小且趋向于均匀分布。变形量越大,合金的室温四点弯曲程度越大,含Ｔｉ５Ｓｉ３较多的Ｔｉ－２４Ａｌ－１１Ｎｂ－５Ｓｉ合金的弯曲强度较高。两种合金的室温弯曲断口形貌均为准解理形式,两相界面结合较强。高温拉伸试验表明：随变形量的增大,Ｔｉ－２４Ａｌ－１１Ｎｂ－２Ｓｉ合金的拉伸强度和塑性都增加。Ｔｉ－２４Ａｌ－１１Ｎｂ－５Ｓｉ合金由于变形量较大和较高的强化相体积含量,拉伸强度明显较Ｔｉ－２４Ａｌ－１１Ｎｂ－２Ｓｉ合金的为高,但塑性却大为降低