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1.
Review of alloy and process development of TiAl alloys 总被引:1,自引:0,他引:1
《Intermetallics》2006,14(10-11):1114-1122
The improved understanding of the factors that control microstructure and properties of TiAl alloys is reviewed together with current work aimed at developing both wrought and cast products. It is suggested that the choice of alloy composition is perhaps far simpler than the complex literature would suggest and the factors that underlie alloy choice will be explained. These factors include the processability of the alloy as well as the properties and examples will be given where this dual approach of defining both processability and properties is central to the successful application. In addition other aspects of processing that will be discussed include cost-effective processing, accuracy of compositional control and control of processing conditions appropriate for the specific alloy. Some current applications of TiAl components are summarised before considering some of the challenges still remaining for TiAl-based alloys. 相似文献
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《Intermetallics》2002,10(3):239-245
The effects of Nb on the mechanical properties, high-temperature deformability and some other basic properties of TiAl–Nb alloys were investigated over a wide compositional range, and an appropriate composition for high-temperature applications was investigated for both wrought and cast materials. The lattice parameter of Ti–50Al–xNb alloy, which is a γ single phase alloy, shows an anisotropic variation with Nb content. This lattice distortion is assumed to be responsible for the strengthening and embrittlement of high-Nb ternary alloys. In the case of wrought materials, no appropriate composition exists in the high-Nb content region since wrought materials require good forgeability and high-temperature strength which are properties of antithesis. In the case of cast materials, however, an appropriate composition exists in the vicinity of Ti–46Al–7.5Nb (at.%). 相似文献
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提高TiAl基合金室温塑性的方法 总被引:17,自引:6,他引:17
TiAl基合金具有密度低、高温性能好等优点,但室温塑性低一直是阻碍TiAl基合金应用的重要原因。本文总结了TiAl基合金的室温塑性的主要影响因素,以及通过添加合金化元素、改善加工工艺等方法来控制显微组织、提高TiAl基金合金的室温塑性的研究进展。 相似文献
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REVIEW ON RESEARCH AND DEVELOPMENT OF MAGNESIUM ALLOYS 总被引:7,自引:0,他引:7
The current research and development of magnesium alloys is summarized. Several aspects of magnesium alloys are described: cast Mg alloy, wrought Mg alloy, and novel processing. The subjects are discussed individually and recommendations for further study are listed in the final section. 相似文献
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Warm deep drawing of wrought magnesium alloy sheets produced by semi-solid roll strip-casting process 总被引:1,自引:0,他引:1
H. Watari N. Koga K. Davey T. Haga M.T. Alonso Ragado 《International Journal of Machine Tools and Manufacture》2006,46(11):1233-1237
This paper is concerned with the development of a continuous strip-casting technology to facilitate the manufacture of magnesium sheet alloys economically whilst maintaining high quality. Established in the paper is warm formability of cast magnesium alloy sheets after being hot rolled by semi-solid roll strip-casting process. It has been found that magnesium sheet with 2.0–4.0 mm thickness could be produced at a speed of 25 m/min. Hot rolling and annealing temperatures during hot rolling were also changed to examine which condition would be appropriate for producing wrought magnesium alloys with good formability. Microstructures of the crystals of the manufactured wrought magnesium alloys were observed. It has been found that a limiting drawing ratio of 2.7 was possible in a warm deep-drawing test of the cast magnesium alloy sheets after being hot rolled. 相似文献
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Owing to their low density and attractive high-temperature properties, gamma titanium aluminide alloys (TiAl alloys, hereafter) have significant potential application in the aerospace and automobile industries, in which these materials may replace the heavier nickel-based superalloys at service temperatures of 600-900℃. Investment casting of TiAl alloys has become the most promising cost-effective technique for the manufacturing of TiAl components. Ceramic moulds are fundamental to fabricating the TiAl casting components. In the present work, ceramic mould with a zirconia primary coat was designed and fabricated successfully. Investment casting of TiAl blades and tensile test of specimens was carried out to verify the correctness and feasibility of the proposed method. The tensile test results indicate that, at room temperature, the tensile strength and the elongation are about 450 MPa and 0.8%, respectively. At 700℃, the tensile strength decreases to about 410 MPa and the elongation increases to 2.7%. Microstructure and mechanical properties of investment cast TiAl alloy are discussed. 相似文献
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Alloy Design of Gamma(TiAl)Alloys 总被引:2,自引:0,他引:2
Young-Won KIM 《金属学报(英文版)》1995,(Z1)
AlloyDesignofGamma(TiAl)AlloysYoung-WonKIM(UES,Inc.,Dayton,OH45432,USA)Abstract:Unbalancedpropertiesforbothfine-grainedgammaa... 相似文献
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Recent developments in engineering γ—TiAl intermetallics 总被引:4,自引:4,他引:4
γ-TiAl based alloys are rapidly being developed for elevated temperature applications,due to their high strength,light mass and good oxidation resistance.However,th disadvantages of TiAl based alloys are low ductility and toughness at room temperature,and poor workability.Grain refinement is one of the most effective ways for improving room temperature tensile properties and hot workability of ordered TiAl based alloys.At present,the majority of research works have focused on alloy modifications through compositional controls,alloying additions,thermo-mechanical processing and production techniques.This article discusses the research status of TiAl based alloys in the aras of microstructure,alloying,processing and applications. 相似文献
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1INTR0DUCTI0NTheTiAlbasedalloyhasbeenknownt0beoneofthemostpromisingcandidatesforhigh-temperaturestructuralapplications['J.Thepr0p-ertiesofthealloysstronglydependedontheir'[z]Ithasbeenthoughtthatthemicrostructures.IthasbeenthoughtthatthefinefullylamelIarmicrostructurehadthebestcombinationofmechanicalproperties['].In0r-dertorefinethecoarsefullylamellarmicrostruc-tureincastcondition,thermomechanicaltreat-ments(TMTs),includingh0textruding,hotrollingandisothermalforging,havebeenused;butbecau… 相似文献
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Theodoros Koutsoukis Makhlouf M. Makhlouf 《International Journal of Cast Metals Research》2017,30(4):231-243
Wrought alloys have low fluidity and are prone to hot tearing, which make them difficult to cast. The presence of eutectic-forming elements in the alloy composition lessens these effects. For this reason, the constituents of casting alloys tend to include a eutectic portion. Typically, silicon is added to aluminium alloys to provide casting ability by forming the aluminium–silicon eutectic. However, the presence of silicon in aluminium alloys is associated with a number of issues that do not allow these alloys to reach their full potential. In this publication we report results of our investigation of three alternative eutectics: Al–6.1Ni, Al–1.8Fe, and Al–1.75Fe–1.25Ni. Our results indicate that these eutectics have satisfactory fluidity and resistance to hot tearing and higher strength than the aluminium–silicon eutectic. We also found that introducing these eutectic compositions into 7075 wrought alloy results in a castable composition with yield strength comparable to that of the wrought alloy. 相似文献
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以Ti-48Al-2Cr-2Nb(at%)合金为研究对象,通过热处理获得近片层和全片层两种显微组织,并在800℃空气条件下,进行了100 h的抗氧化性实验。利用OM、SEM、TEM、XRD和EDS对试样的微观结构、相组成及微区成分进行了分析。恒温氧化动力学结果表明:在800℃空气条件下,对于近片层和全片层两种Ti Al合金组织,其恒温氧化动力学曲线符合近抛物线规律,且近片层组织合金的抗氧化性能优于全片层组织。基于氧化动力学曲线、组织结构、氧化膜结构、氧化表面形貌分析,表明Ti Al合金的片层组织结构对其氧化行为具有不可忽视的影响。 相似文献
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研究了元素Y和Nb对用熔体快淬法制备的TiAl基快速凝固合金组织及性能的影响。发现添加Y的快速凝固TiAl合金主要为等轴晶,主要组成相为α2和少量的γ相。随着Y含量的增加,γ相的含量增加,快速凝固TiAl合金的组织逐渐细化。不同Nb含量的快速凝固TiAl合金的组织为块状结构和层片状结构,主要由γ和α2两相组成,层片间距显著细化,为15~17nm。快速凝固TiAl合金的硬度比其铸态合金显著提高。 相似文献
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As a typical intermetallic material, TiAl is inevitably difficult to process by conventional methods. Additive manufacturing (AM) has recently become a new option for making net-shape TiAl components. Among all AM methods, electron beam melting (EBM) shows the potential to make TiAl components with good mechanical properties and is used for low pressure turbine blades. The mechanical properties, including tensile and compression properties, fracture toughness, fatigue and creep properties of EBM TiAl are reviewed and compared to the conventionally fabricated alloys. Results show that the tensile strength of EBM alloys is higher than cast alloys, and other properties are comparable to the cast/forged alloys. The sensitivity of mechanical properties and microstructure to EBM processing parameters is presented. Issues including layered microstructure, anisotropy in mechanical properties, and fatigue failure from defects are also reviewed. Finally, some opportunities and challenges of EBM TiAl are identified. 相似文献
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《Intermetallics》2017
In the present work, the microstructure and compression properties of two novel γ(TiAl) based alloys, Ti-45Al-5Fe and Ti-45Al-5Fe-5Nb, have been investigated. Both alloys had a relatively fine as-cast structure generally consisting of the γ(TiAl) and τ2(Al2FeTi) phases with a minor amount of the α2(Ti3Al) and β(B2) phase. The compression properties of the novel alloys were measured at room and elevated temperatures. The Ti-45Al-5Fe-5Nb alloy showed higher room temperature ductility and similar strength at room and elevated temperatures as well as improved workability at elevated temperatures as compared to β-solidifying γ(TiAl) alloys of last generation (TNM alloys). 相似文献
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This paper investigated high-damping Cu-Al-Be-B cast alloys using metallographic analysis, X-ray diffraction (XRD) and electrical resistance measurements for transformation temperatures. The results showed that beryllium can stabilize β phase, resulting in a thermo-elastic martensite microstructure leading to high-damping capacity in cast Cu-Al-BeB alloys. Trace additions of boron to Cu-Al-Be alloys can significantly refine the grains, providing high strength and ductility to the alloys. A factorial design of experiment method was used to optimize the composition and properties of cast Cu-Al-BeB alloys. The optimal microstructure for thermo-elastic martensite can be obtained by adjusting the amounts of aluminum and beryllium to eutectoid or pseudo-eutectoid compositions. An optimized cast Cu-Al-Be-B alloy was developed to provide excellent mechanical properties, tensile strength σb = 767 MPa, elongation δ = 7.62 %, and damping capacity S. D.C =18.70%. 相似文献
19.
Application of cast gamma TiAl for automobiles 总被引:20,自引:0,他引:20
Studies of cast gamma TiAl applied for engine valves and turbocharger confirmed excellent performances. The durability of TiAl valves was also proven. Two cast gamma TiAl alloys were developed for the engine valves and the turbine wheels of turbochargers. New precision casting process of LEVICAST and induction brazing process of the gamma TiAl and alloy steels were proposed as advanced processing technologies. 相似文献