钛合金在硅酸盐溶液中微弧氧化陶瓷膜的组织结构

利用微弧氧化方法在硅酸盐溶液中在Ｔｉ－６Ａｌ－４Ｖ合金表面生长出一层厚度达５０μｍ的陶瓷氧化膜,并用Ｘ射线衍射（ＸＲＤ）、扫描电镜（ＳＥＭ）初步研究了氧化膜的组织结构。该氧化膜由大量金红石型ＴｉＯ２、ＳｉＯ２非晶相及少量锐钛矿型ＴｉＯ２相组成,且膜内层金工石含量比膜外层结相都是由微弧区熔融快速冷却形成的。硅元素已扩散到膜内层,Ｔｉ、Ｓｉ元素在膜内部分布是不均匀的。     

钛铝高温氧化表面分析

将５种铸态ＴｉＡｌ置于７００℃～１０００℃静止空气中断续氧化１００ｈ。采用ＸＲＤ和ＳＥＭ／ＥＤＳ分析技术,观察分析了ＴｉＡｌ氧化后的表面形貌、相组成及分布状况,结果表明：氧化产物主要为金红石型Ｒ－Ｔ和刚玉型α－Ａ１２Ｏ３;低温、短时氧化时,氧化产物呈混合形式存在;高温、长时化时,在混合氧化物之外易形成纯Ｒ－ＴｉＯ２晶体层。     

Cr对TiAl金属间化合物高温氧化性能的影响

研究了Ｔｉ－５０Ａｌ，Ｔｉ－４５Ａｌ－１０Ｃｒ和Ｔｉ－５０Ａｌ－１０Ｃｒ（原子分数，％）合金在８００－１１００℃下的高温氧化性能。结果表明，Ｔｉ－４５Ａｌ－１０Ｃｒ合金在８００和９００℃形成的氧化膜具有与ＴｉＡｌ合金同样的分层结构，外层为ＴｉＯ２，内层为ＴｉＯ２和Ａｌ２Ｏ３的混合氧化物，在内外氧化层中间有一富Ａｌ２Ｏ３４的中间层，但内氧化层中有大量Ｃｒ掺杂，其氧化增重比Ｔｉ－５０Ａｌ的大，而１００     

离子束增强沉积氮化硅膜及TiAl抗高温氧化性能的改善

用离子束增强沉积（ＩＢＥＤ）方法在金属间化合物ＴｉＡｌ上合成厚度为０．５，１，和２μｍ的氮化硅薄膜。所形成的薄膜为非晶态，膜与基底间存在混合的过渡区，膜与基底结合紧密用ＡＥＳ，ＸＲＤ和ＸＰＳ研究薄膜的组成和结构，高温循环氧化结果表明，经沉积膜的ＴｉＡｌ试样的抗氧化性能显著提高其中沉积０．５μｍ薄膜的试样表现出极好的抗循环氧化性能由ＳＥＭ及ＥＤＳ分析得出，良好的高温稳定性能、高的膜／基底结合力和形成富Ａｌ２Ｏ３和硅化物的保护层是提高ＴｉＡｌ抗高温氧化性能的主要因素．     

Al-Ti-C中间合金细化剂的组织及其细化性能

以一析方法在低温、低搅拌条件下成功地制备了几种成分的Ａｌ－Ｔｉ－Ｃ中间合工采用Ｘ射线衍射（ＸＲＤ）,扫措电镜（ＳＥＭ）和能谱分析（ＥＤＳ）等手段对中间合金的相组成和显微组织进行了综合分析,结果表明,Ａｌ－Ｔｉ－Ｃ中间合中的第二相粒子为块状Ａｌ３Ｔｉ和亚微米尺寸的非整化合物ＴｉＣｘ,其中ｘ在０．４９～０．７８之间不等,细化结果表明。Ａｌ－Ｔｉ－Ｃ对工业纯铝具有良好的晶粒细化效果,细化的闰核心为Ｔｉ,     

Al含量对二元Ti—Al合金高温氧化行为的影响

研究了Ａｌ含量为３３．３ａｔ％～５２ａｔ％Ａｌ的５种二元Ｔｉ－Ａｌ合金在８００℃和９００℃空气中的恒温氧化行为，用Ｘ射线衍射仪和扫描电子显微镜对其氧化产物，氧化物表面形貌和氧化层剖面结构进行了分析，研究发现：在该Ａｌ含量范围内，二元Ｔｉ－Ａｌ合金的氧化层均由具有典型形貌特征的一系列氧化薄层组成，而且在氧化层中均未形成连续致密分布的Ａｌ２Ｏ３；Ａｌ含量对氧化层中Ａｌ２Ｏ３的形态，分布以及恒温氧化反应     

EFFECT OF ELECTRODEPOSITED Ni-La_2O_3 COMPOSITE FILM ON OXIDATION RESISTANCE OF γ-TiAl

用Ｎｉ与Ｌａ２Ｏ３微粒共电沉积的方法,在γ－ＴｉＡｌ金属间化合物表面覆盖一种Ｎｉ－Ｌａ２Ｏ３抗氧化性功能复合镀层,恒温和循环氧化动力学表明,γ－ＴｉＡｌ表面沉积复合镀层后,氧化速度显著降低,氧化皮粘附性明显增强,ＳＥＭ／ＥＤＸ和ＥＰＭＡ分析结果表明,γ－ＴｉＡｌ表面沉积复合镀层后,在氧化时抑制了ＴｉＯ２氧化物的生长,并促进了两层连续的Ａｌ２Ｏ３层分别在复合镀层的氧化层下以及接近基体的区域形成。复合     

高速电弧喷射沉积Fe3Al涂层研究

采用自行研制的电弧喷涂Ｆｅ３Ａｌ合金粉丝材料,成功地用高速电弧喷涂技术制备出Ｆｅ３Ａｌ化合物涂层运用能谱技术（ＥＤＸＡ）、Ｘ射线衍射仪（ＸＲＤ）、扫描电子显微镜（ＳＥＭ）和图像分析仪对涂层成分、显微组织、涂层相结构和组成进行了分析,结果表明,支由以Ｆｅ－２９Ａｌ为主的Ｆｅ３Ａｌ和少量Ｆｅ３Ａｌ基体相和约２０％的α－Ａ１２Ｏ３相组成。对比研究了Ｆｅ３Ａｌ涂层和电站锅炉水冷壁材料２０Ｇ的６５０℃氧化动     

铝,硅共渗提高γ／γ′—α—Mo定向共晶合金抗氧…

用ＸＲＤ、ＥＰＭＡ、ＳＥＭ、天平等分析手段，对γ／γ′－α－Ｍｏ定向共晶合金共渗Ａｌ、Ｓｉ前后、氧化前后的金相组织、相组成、氧化产物等进行了分析。对实验结果进行了讨论。采用粉末包埋Ａｌ、Ｓｉ共渗方法，在γ／γ′－αＭｏ定向共晶合金表面可形成抗氧化ＮｉＡｌ、Ｍｏ（Ａｌ、Ｓｉ）２相。在１０００℃、１１００℃空气中氧化时，Ｍｏ（Ａｌ，Ｓｉ）２相由氧化前的纤维状向不连续的、弥散的颗粒状转变，进一步提高了合     

自生复合材料（Al—TiB2—TiC）的燃烧合成研究

本文研究了Ａｌ－Ｔｉ－Ｂ４Ｃ体系的燃烧合成过程，用粉末（Ａｌ，Ｔｉ，Ｂ４Ｃ）通过燃烧方法，来制备复合材料（Ａｌ－ＴｉＢ２－ＴｉＣ）。采用ＤＴＡ、ＸＲＤ和ＳＥＭ译复合材料的形成和结果进行了分析研究，得到如下结果：分别用８０％Ａｌ＋２０％（３Ｔｉ＋Ｂ４Ｃ），９０％Ａｌ＋１０％（３Ｔｉ＋Ｂ４Ｃ）原料粉末，通过忆热可得到Ａｌ－ＴｉＢ２－ＴｉＣ，在制备过程中会产生少量的ＴｉＡｌ３．     

Isothermal oxidation behavior of Ti3Al-based alloy at 700-1000℃ in air

The isothermal oxidation behavior of a Ti3Al-based alloy (Ti-24Al-14Nb-3V-0.5Mo-0.3Si, molar fraction, %) at 700- 1 000 ℃ in air was investigated. The oxidation kinetics of tested alloy approximately obeys the parabolic law, which shows that the oxidation process is dominated by the diffusion of ions. The oxidation diffusion activity energy is 241.32 kJ/mol. The tested alloy exhibits good oxidation resistance at 700 ℃. However, when the temperature is higher than 900 ℃, the oxidation resistance becomes poor. The XRD results reveal that the oxide product consists of a mixture of TiO2 and Al2O3. Serious crack and spallation of oxide scale occur during cooling procedure after being exposed at 1 000 ℃ in air for 16 h. According to the analysis of SEM/EDS and XRD, it is concluded that the Al2O3 oxide forms at the initially transient oxidation stage and most of it keeps in the outer oxide layer during the subsequent oxidation procedure.     

The Isothermal and Cyclic Oxidation Behavior of a Titanium Aluminide Alloy at Elevated Temperature

The isothermal and cyclic oxidation behavior of Ti-47Al-2Mn-2Nb with 0.8 vol.% TiB₂ particle-reinforced alloy was investigated in air between 700 and 1000 °C. In the study, the kinetics of isothermal and cyclic oxidation were performed by using a continuous thermogravimetric method which permits mass change measurement under oxidation conditions. The oxide scales and substrates were characterized by scanning electron microscopy with energy-dispersive x-ray analysis and x-ray diffraction. At 700 and 800 °C, the alloy showed an excellent oxidation resistance under isothermal and cyclic conditions. After exposure to air above 800 °C, the outer scale of the alloy was dominated by a fast-growing TiO₂ layer. Under the coarse-grained TiO₂ layer was the Al₂O₃-rich scale, which was fine-grained. At 900 and 1000 °C, the extent of oxidation increased clearly. The oxidation rate follows a parabolic law at 700 and 800 °C. However, the alloy, upon isothermal oxidation at 900 °C, can be divided into several stages. During the cyclic oxidation at 900 and 1000 °C, partial scale spallation takes place, leading to a stepwise mass change.     

High temperature oxidation of Ti−48%Al−2%W intermetallics

Powder metallurgically produced Ti-48% Al-2%W alloys were oxidized between 800 and 1050°C in air. The W-addition was quite effective in providing isothermal and cyclic oxidation resistance. The alloys oxidized parabolically up to 1050°C during isothermal oxidation, with small weight gains. The scales were adherent up to 900°C during cyclic oxidation. Oxide scales consisted primarily of an outer TiO₂ layer, an intermediate Al₂O₃ layer, and an inner (TiO₂+Al₂O₃) mixed layer. Tungsten was present below the intermediate Al₂O₃ layer. and also at the scale-matrix interface as W-enriched compounds. Below the oxide scale, a Ti₃Al zone containing some W and O existed.     

Effect of enamel coating on long-term oxidation and hot corrosion behavior of Ti-24Al-17Nb-0.5Mo alloys

The effect of enamel coating on long-term isothermal oxidation at 700 ℃ and cyclic oxidation at 800 ℃ in air and hot corrosion resistance of Ti-24Al-17Nb-0. 5Mo in 75% (Na2SO4 K2SO4 ) 25% NaCl (mass fraction) molten mixed salts at 700 ℃ was investigated. The results indicate that Ti-24Al-17Nb-0.5Mo alloy exhibits relatively poor long-term oxidation resistance due to the formation of Al2O3 TiO2 Nb2O5 mixed scales and poor hot corrosion resistance due to the spallation of scales formed in molten (Ns, K)2 SO4 NaCl. Enamel coating can effectively protect Ti-24Al-17Nb-0.5Mo alloy from long-term oxidation at high temperature in air and remarkably improve the hot corrosion resistance of Ti-24Al-17Nb-0. 5Mo alloy, and can act as the barrier to suppress the migration of oxygen and corrosive ions into the substrate.     

Comparison of molybdenizing and NiCrA1Y coating on Ti and Ti-6A1-4V

Two surface treatments, molybdenizing and depositing NiCrAIY coating, were applied to improve the microhardness and the oxidation re-sistance of titanium and Ti-6Al-4V. Coupons were analyzed using optical microscopy (OM), scanning electron microscopy (SEM) with X-ray energy dispersive spectrometer (EDS), and X-ray diffraction (XRD). Vickers hardness and isothermal oxidation tests were carded out to evaluate the effects of these two surface treatments on the microhardness and oxidation resistance of the substrates. The post vacuum heat treatment of the NiCrAlY coating and the molybdenizing parameters were also discussed. It is found that molybdenizing can obviously in-crease the surface hardness of titanium due to the formation of β,α", and α' phases in the diffusion layer. As γ' phase is formed after vacuum heat treatment, the NiCrAIY coating is effective in improving the surface hardness of Ti-6Al-4V. The NiCrAlY coating can obviously de-crease the oxidation rate of Ti-6Al-4V at 700-900℃, which can be attributed to the formation of Al2O3 and Cr2O3 mixed scale during the oxidation.     

High-Temperature Oxidation Behavior of Ti-22Al-27(Nb, Zr) Alloys

研究了Ti2Al Nb基合金Ti-22Al-(27-x)Nb-x Zr(x=0,1,6,at%)在650~800℃的氧化行为。采用XRD和SEM等测试技术对此温度区间形成的氧化层特征进行了分析。结果表明,相比Ti-22Al-27Nb,含锆合金具有较好的抗氧化性能。Ti-22Al-(27-x)Nb-x Zr合金在650℃氧化100 h,主要氧化产物为Ti O2,而在800℃氧化100 h,Ti O2,Al2O3和Al Nb O4为主要产物,但是在Ti-22Al-21Nb-6Zr合金中还有Zr O2生成。Ti-22Al-26Nb-1Zr合金具有优异抗氧化性能,归因于氧化产物细化形成了致密的氧化层,而Ti-22Al-21Nb-6Zr合金,虽然在800℃也形成了较多Al2O3,但是氧化层中的Zr O2为氧的快速扩散提供通道,进而导致该合金氧化增重明显。     

Effects of Nb and Si on high temperature oxidation of TiAl

The isothermal oxidation behavior of TiAl based alloys at 900℃ in air with a combination of Nb (5%-10%, mole fraction) and Si (1%-5%, mole fraction) was investigated. The microstructure and the composition of the oxidation scale were studied by using XRD, TEM and EPMA. The results show that the combination of Nb and Si can improve the oxidation resistance of the alloys significantly. The element Si can change the typical microstructure of oxidation scale on TiAl based alloys. In alloys with Si addition, the compact Al2O3 forms in the interior side of oxidation scale. When x (Si)3%, the Ti5Si3 phase forms and the coarse crystal TiO2 forms on Ti5Si3 phase after oxidation. The increase of Nb content in the TiAl based alloys impedes the growth of Ti5Si3 phase, and the formation of TiO2 on surface and on Ti5Si3 phase is also impeded.     

V/Nb对Ti-45Al-9(V, Nb, Y)合金抗氧化性能的影响

βγ-TiAl合金具有良好的高温变形能力,为TiAl合金的发展开辟了新的途径。成功制备了不同x=V/Nb(x=1,1.5,2,3.5)的βγ-TiAlTi-45Al-9(V,Nb,Y)合金,研究了上述合金在800℃静止空气中的氧化行为。结果表明:当x=1时,Ti-45Al-9(V,Nb,Y)合金中形成条带状、连续致密的Al2O3氧化层,显著提高了合金的抗氧化能力。随着x=V/Nb的增加,Al2O3氧化层厚度变薄,合金的抗氧化能力下降。     

EFFECT OF MICROSTRUCTURES ON CYCLIC-OXIDATION BEHAVIOUR OF TiAl ALLOY

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

Effect of Nb on oxidation behavior of high Nb containing TiAl alloys

The isothermal oxidation behavior of Ti-45Al-8Nb and Ti-52Al-8Nb alloys at 900 °C in air was investigated. The early oxidation behaviors were studied by using XPS and AES. And the microstructure and the composition of the oxidation scale were studied by using XRD and SEM. The results show that the oxidation behavior of TiAl alloy is significantly improved by Nb addition. Nb substitutes for Ti in TiO₂ as a cation with valence 5, and thus to suppress TiO₂ growth. The (Ti,Nb)O₂-rich layer is a dense and chemically uniform which is more protective than the TiO₂ layer. Nb addition also lowers the critical Al content to form an external alumina. Nb₂Al phase is formed in the metallic matrix at the oxide–metal interface on the high Nb containing TiAl alloys.