钛锆铪分会2007年年会暨中国钛工业发展论坛

1 关于年会 近年来，中国钛工业发生了深刻的变化：一方面是我国国民经济持续高速发展，特别是目前我国经济发展正处于城市化阶段，国家对有色金属材料的需求强劲，提升了对海绵钛和钛加工材的需求；另一方面是对中国钛工业投资热情高涨，中国钛工业快速发展，2007年中国海绵钛和钛加工材呈翻番式增长已成定局，并已由一个海绵钛和钛加工材的净进口国变成了净出口国，中国钛工业对世界的影响大增。在这样的形势下，研究和判断中国钛工业的走势，分析明了中国钛工业的不足，分析世界钛市场及其走势，为企业找市场，把企业推向国内外两个市场，了解钛的新技术和新的应用领域，就成了本次会议的主题。     

关于召开钛锆铪分会第三次会员大会暨2006年年会的通知

近年来，随着我国国民经济持续、高速、健康的发展，我国钛工业也同步持续、高速的发展。截止2005年底，我国钛加工材的需求量达到12200t，并出现了第一个万吨级产能的海绵钛大厂。2006年，我国钛工业还将有一个巨大的增长，海绵钛和钛加工材的产量将双双过万吨，并将出现一个优质钛锭产能过万吨的钛加工材大厂。在这样的大好形势下，怎样使我国钛工业持续、高效、与环境友好和谐的发展，是我国钛业工作者亟待思考的课题。     

正在崛起的中国钛工业

概述了跨入新世纪以来中国钛产业及钛科技的发展概况,分析了中国钛产业快速发展的原因。中国钛工业已经进入快速发展期。自2001年以来,6年时间里钛加工材年增长约30%。2006年,中国的海绵钛和钛材产量分别达到18000t和13000t。最后展望中国钛产业的未来。可以预测,在不久的将来,中国的海绵钛和钛材产量都会超过30000t/a。中国钛工业前景光明。     

2005年世界钛工业发展状况及展望

分析了2005年间美国、俄罗斯、日本和中国等各主要钛生产国的钛工业发展状况。2005年美国3大钛生产商Timet，RTI和ATI的销售额分别比2004年增长了50％，55．8％和30％；俄罗斯的唯一钛加工材生产商VSMPO的销售额同比增长105．7％；日本的海绵钛和加工材生产量分别增长26％和4．4％；中国生产的海绵钛和钛材同比分别增长100％和20％，世界钛工业呈现出一片欣欣向荣的景象。展望2006年及未来，全球钛市场将随着全球经济的好转、工业和航空工业的发展以及应用领域的拓宽而持续稳定走强。     

中国钛工业发展与评述

介绍了历年中国海绵钛及钛锭产能的变化、钛加工材消耗量增长概况、钛产品结构调整及钛加工材在各领域的消费比例。分析了世界钛工业近期的发展及研究动态。指出目前中国钛工业需关注的问题:①钛资源的合理利用;②海绵钛新型制备技术的开发;③海绵钛生产中造成的环境污染;④低水平重复过度设资;⑤上下游企业的联合;⑥实用技术的开发。并对中国钛工业的发展前景进行了展望。     

2000年日本钛市场预测

据日本钛协会预测,２０００年日本海绵钛的总产量估计要比１９９９年的１９ ５２２ｔ下降１０．５％,为１７ ５００ｔ但钛加工材的产量预计要比１９９９年的１１４７６ｔ增加４．６％,为１２０００ｔ． ２０００年,由于美国和欧洲民用飞机的生产开始缩减,海绵钛的出口量预计要比上年减少 ２８．７％,从７０１５ｔ降为５ ０００ｔ．日本国内海绵钛的用量预计可能保持上年的水平,几乎不变,为１２ ５００ｔ（１９９９年为１２ ５３７ｔ）;钛的加工材预计可能有所增加,生产厂家估计首先要安排使用库存的海绵钛．另外,代理商则预先考…     

美国、日本和中国钛工业发展评述

简要叙述了美国、日本和中国近年钛工业的状况和展望，从钛矿资源、海绵钛、钛加工材、钛应用开发、钛合金研究开发等方面比较了各自发展的特点。     

2007年上半年我国钛工业运行情况

评述了2007年上半年我国钛工业的运行情况。2007年上半年我国钛工业突飞猛进，海绵钛产量达到20098t，比去年同期增加203．5％；钛加工材产量达11311t，比去年同期增加84．5％；海绵钛的净出口量为2150t，钛加工材的净出口量为1617t。中国经济的快速发展和有色金属的高价位，为钛需求的暴发式增长提供了可能。文章最后提出了当前钛工业应十分注意的几个问题，以引起业内人士的关注和思考。     

我国钛加工业的发展战略

1　前　言中国钛资源居世界首位 ,已探明的钛储量为 7.0 3× 10 8t,占世界钛储量的一半。中国钛加工业已有近半个世纪的历史。 2 0世纪5 0年代中期 ,在北京开始了钛加工的研究工作 ;6 0年代初期 ,在沈阳开始了钛的半工业化生产 ;6 0年代中期 ,在贵州遵义和陕西宝鸡分别建设了海绵钛和钛加工材生产厂 ,这两个钛专业生产厂的建立和投产 ,表明中国已成为世界钛工业国并确立了其地位。自此 ,中国海绵钛和钛加工材产量逐年增加 (图1) ,现已形成 36 0 0 t/ a海绵钛和 30 0 0 t/ a钛加工材的生产能力。图 1　我国历年海绵钛和钛加工材产量及预测2　…     

日本钛市场回顾与展望

１９９９年继１９９８年之后,日本钛的需求大幅度减少,目前尚未看出有恢复的征兆．由于钛加工材在日用品、汽车等新领域已开始实质性使用,预计２０００年钛加工材日本国内需求比１９９９年有所增长;由于东南亚经济复苏,以及延期的ＴＰＡ（对苯二甲酸）项目重新开工,预计今年日本钛材的出口量与１９９９年相当．日本钛协会预测,２０００年下半年,日本钛工业将逐渐复苏．１　１９９９年日本钛市场回顾１．１海绵钛 １９９９年,日本内需及出口海绵钛的需求量达１９ ５５２ｔ,比１９９８年减少１８％,是自１９９５年以来首次跌至２万…     

Mechanical behavior of microstructure engineered multi-length-scale titanium over a wide range of strain rates

In this work, we studied the mechanical behavior of commercial purity Ti powder consolidates with an engineered microstructure containing multiple-length-scale features, over a wide range of loading rates. The microstructural length scales were engineered by mixing powders of different sizes, followed by either hot quasi-isostatic forging (QIF) or spark plasma sintering (SPS). We used electron backscatter diffraction and transmission electron microscopy to examine the microstructure of the Ti materials. A bimodal grain size distribution has been achieved for the majority of the QIFed samples, while those consolidated via SPS exhibit a near-equiaxed morphology. All samples synthesized with powders milled in liquid argon show considerable uniform plastic deformation under quasi-static compression, with no failure, and their strength values are considerably high when compared to those of commercial purity Ti. Moreover, the materials consolidated from milled powders exhibit adiabatic shear banding under high rate uniaxial compression via the Kolsky bar technique. Samples prepared from a preselected proportion of powders milled in liquid nitrogen showed quasi-static strength as high as 2000 MPa, and dynamic peak stress as high as 2700 MPa, comparable to the strength of high-strength steels. However, these super-strong Ti samples are brittle under both quasi-static and dynamic compression. The strengthening of these Ti materials with an engineered microstructure is primarily attributed to the presence of interstitials. Twins were observed in nanometer-sized grains in the strongest and brittle samples, along with evidence of the TiN phase, which was attributed to exposure to a high level of nitrogen introduced during milling in liquid nitrogen. The high rate behavior can be rationalized on the basis of an adiabatic shear band model that takes into account strain and strain rate hardening.     

Characteristics and wear performance of borided Ti6Al4V alloy

In this study, a 10 µm thick uniform boride layer, composed of TiB₂ and TiB phases, was formed on the surface of a Ti6Al4V alloy using a pack boriding technique. The hardness of the boride layer was over 2000 HV. Beneath the boride layer, a boron diffusion zone (BDZ) appeared with a thickness of about 50 µm. The microstructure of the BDZ was composed of randomly oriented TiB whiskers mixed with the structure of the base metal. In the BDZ, hardness decreased gradually towards the base metal owing to the reduction of the TiB volume fraction. The borided alloy exhibited excellent wear resistance along with a lower coefficient of friction against sapphire ball under both dry and smear lubricated sliding conditions when compared to the as-received state.     

Ti53311S钛合金热变形的组织和机制分析

用Gleeble-1500型热模拟试验机对Ti53311S钛合金在温度为880～1080℃,应变速率为0.001～10 s-1的条件下进行高温压缩变形行为的研究.测试了其真应力.真应变曲线,采用双曲正弦本构方程计算出激活能,双相区为641 kJ/mol,β相区为244 kJ/mol.观察了变形后的显微组织,并分析了其变形机制.结果表明:该合金对温度和应变速率敏感,不同变形条件下应力值变化很大;应变速率敏感指数(m)随温度升高而降低,而变形激活能(Q)随温度升高而增大.合金的变形机制在双相区为晶界滑移和晶粒球化,在β单相区为动态回复.     

钛合金表面Ti/TiB2仿生多层膜的断裂韧性研究

根据贝壳珍珠层的结构特点,以金属Ti层为软质层,对TiB2陶瓷薄膜进行仿生增韧处理,并通过压痕法研究了Ti/TiB2仿生多层膜的断裂韧性。研究结果表明：随着调制比(Λ, tTiB2:tTi)的增大,多层膜的断裂韧性先增大而后减小,当Λ为5时,多层膜的断裂韧度达到最大值(KIC=2.68 MPa     

铸造工艺对钛合金Ti5Al2.5Sn ELI铸态组织及性能的影响

Ti5Al2.5Sn ELI钛合金是航空航天等领域重要的结构材料。本工作采用3种铸型同炉浇注的方法研究了铸造工艺对该合金铸态组织和室温拉伸性能的影响。结果表明,该合金石墨型铸造试样表面粗糙,陶瓷型和金属型的则较光滑;石墨型试样宏观组织为大量等轴晶和少量柱状晶,金属型的为少量等轴晶和大量柱状晶,陶瓷型的为粗大柱状晶和等轴晶;不同工艺下显微组织均由不规则边界α集束组成,其内部为片状α相,石墨型的α片宽度最小,金属型的次之,陶瓷型的最大;该合金铸态抗拉强度715~731 MPa、伸长率8%~15%,石墨型的伸长率最高,金属型的次之,陶瓷型的最低,铸造工艺对该合金塑性影响强烈,但对强度的影响较小;铸型表面形貌、导热系数、α集束大小及α片厚度的不同是上述现象产生的主要原因。     

Dynamic response and plastic deformation behavior of Ti–5Al–2.5Sn ELI and Ti–8Al–1Mo–1V alloys under high-strain rate

Split Hopkinson pressure bar test system was used to investigate the plastic deformation behavior and dynamic response character of a-type Ti–5Al–2.5Sn ELI and near a-type Ti–8Al–1Mo–1V titanium alloy when subjected to dynamic loading. In the present work, stress–strain curves at strain rate from 1.5 9 103to 5.0 9 103s-1were analyzed, and optical microscope(OM) was used to reveal adiabatic shearing behavior of recovered samples. Results show that both the two alloys manifest significant strain hardening effects. Critical damage strain rate of the two alloys is about 4.3 9 103s-1, under which the impact absorbs energy of Ti–5Al–2.5Sn ELI and Ti–8Al–1Mo–1V are 560 and 470 MJ m-3, respectively. Both of them fracture along the maximum shearing strength orientation, an angle of 45° to the compression axis. No adiabatic shear band(ASB) is found in Ti–5Al–2.5Sn ELI alloy, whereas several ASBs with different widths exist without regular direction in Ti–8Al–1Mo–1V alloy.     

Thermophysical properties of a Ti–44%Al–8%Nb–1%B alloy in the solid and molten states

The families of titanium aluminide intermetallic alloys have attractive high temperature mechanical properties which make them potential candidate materials for a wide range of applications, particularly in the aeronautic and automobile sectors. The development of appropriate manufacturing techniques is an essential stage in the engineering exploitation of these materials, e.g., Induction Skull Melting is one of the techniques which needs to be optimised for the casting of titanium aluminides. Research is underway to develop a computer model of this process but data are required for the key thermophysical properties. Pulse-heating techniques have been used to measure properties for the Ti–44Al–8Nb–1B system. Rectangular samples have been prepared and are resistively heated as part of a fast capacitor discharge circuit. Time-resolved measurements with sub-μs resolution of currents through the specimen were made with a Pearson probe current monitor using the induction principle. Voltages across the specimen were determined with knife-edge contacts and voltage dividers, and radiance temperatures of the sample were measured with a pyrometer. These measurements allow the calculation of specific heat and dependencies between enthalpy, electrical resistivity and temperature of the alloy up into the liquid phase. Data for thermal diffusivity have been obtained by using the Wiedeman–Franz relation. The results are compared with those obtained using DSC and the four-probe method to measure the temperature dependence of the resistivity.     

Synthesis and characterization of Li4Ti5O12 via a hydrolysis process from TiCl4 aqueous solution

Spinel-type lithium and titanium composite oxide Li4Ti5O12 was successfully synthesized via a novel hydrolysis method followed by calcination using titanium tetrachloride(TiCl4) and lithium hydroxide(LiOH H2O) as raw materials. Three major factors, including LiOH concentration, LiOH dosage, and hydrolysis temperature were studied for optimizing the synthetic conditions to obtain a phase-pure Li4Ti5O12. The physical and electrochemical properties of samples were characterized by X-ray diffraction(XRD), thermogravimetric analysis(TGA), fourier transform infrared spectroscopy(FT-IR), scanning electron microscopy(SEM), and constant current discharge–charge test. The FT-IR results indicate the presence of [TiO6]octahedra. The SEM images show that the Li4Ti5O12 precursor obtained is an amorphous solid with an irregular and rough morphology. It is revealed that the phase-pure spinel Li4Ti5O12 powders with well crystallization and regular morphology can be obtained by calcining the precursor at800 °C for 6 h. The constant current discharge–charge tests indicate that the Li4Ti5O12 material delivers an excellent cycling ability, maintaining 93.8 % of its initial specific capacity after 60 cycles at a current density of 0.5C.     

RESEARCH ON LASER SOLID FORMING OF A FUNCTIONALLY GRADED TI-TI2ALNB ALLOY

采用激光立体成形技术制备了从Ti到Ti2AlNb成分连续渐变、外形规则、高度为17 mm的梯度材料. 分析了梯度材料的组织及相结构演变规律和硬度变化规律. 随着Al和Nb成分的提高,Ti-Ti2AlNb功能梯度材料的相呈现α' → α+β → α+α' → α' → α+β → α+β/B2+α2 → β/B2+α2 → β/B2 →B2+ α2+O→ B2的演变过程, 实现了由$α$型钛合金经过α+β型及β型钛合金向Ti2AlNb基合金的转变. 硬度值HV从底部纯Ti的170连续 渐变到顶端Ti2AlNb的470. 基于钛合金富Ti区非平衡相图, 并结合Al和Nb元素在钛合金中对α, β和α2稳定性的影响分析, 对梯度材料在激光立体成形过程中的相演化过 程进行了解释.     

Ti5Al2.5Sn ELI钛合金铸造组织与力学性能研究

Ti5Al2.5Sn ELI钛合金是航空航天等领域的重要结构材料。本文采用TEM、XRD等分析方法对该合金的铸造组织和力学性能进行了研究。结果表明,Ti5Al2.5Sn ELI钛合金铸态显微组织由α相组成,并呈片状分布,经HIP处理后显微组织未有明显变化,缺陷弥合部位有再结晶现象;该合金在常温下具有中等强度和良好塑、韧性,疲劳裂纹扩展速率较低,断裂韧性采用25 mm试样无法获得准确K_Ic值,只能得到条件值K_q,ELI级合金的抗断裂和抗裂纹扩展能力高于非ELI级合金。