用Matano法计算Ti基Al膜的反应扩散系数

本文主要是通过Ti基与Al膜反应动力学提供的浓度分布曲线,用Matano方法计算Ti基Al膜在Ti相变点(880℃)上、下的反应扩散系数,求出扩散激活能,找出了扩散系数与温度和成分的变化规律。     

Ti-Al系中TiAl和Ti_3Al相层生长动力学和互扩散

本文研究了Ti衬底与A1膜(1.25～1.35μm)间,在温度580～800℃反应时,金属、TiAl及Ti_3Al相层生长规律,并用Boltzmann-Matano-Heumann和Wagner方法计算了Al在化合物中的互扩散系数和扩散激活能,找出了扩散系数随温度和时间的变化规律,计算结果表明,A1在TiAl及Ti_3A1中的扩散激活能分别为0.82±0.1eV和0.65±0.1eV。     

W–Ti合金互扩散及β结构稳定性研究

通过测量相同时间、不同温度下制备的W/Ti扩散偶成分和显微硬度,研究了W–Ti合金的扩散特性和机理,计算了W/Ti互扩散系数(单位:cm~2·s~(-1)),并利用MS软件对Ti原子数分数为12.5%~50%的W–Ti二元合金的能量、电子结构进行了理论计算。结果表明:W与Ti发生互扩散,其中W在Ti中的扩散速度远高于Ti在W中的扩散速度;在1100~1300℃时,W基固溶体中的互扩散系数公式为2.6×10~(-5)exp(-385.3/k T),Ti基固溶体中的互扩散系数公式为4.1×10~(-2)exp(-285.1/k T),其中,T为扩散温度,k为扩散距离;随着Ti原子数分数的升高,W–Ti合金的β结构稳定性降低。     

用反应烧结和反应熔化法制取TiAl-TiB_2复合材料

Ti Al基合金的优点是密度低、比强度高、刚度大、抗裂纹稳定性好 ,耐热可达90 0℃～ 10 0 0℃ ,Ti- Al的强力共价键可保证它有高的扩散激活能 ,从而能在 90 0℃以下阻止蠕变过程的发展。Ti Al的室温弹性模量为 16 0 GPa～ 175 GPa,高于一般钛合金(10 0 GPa) ,但低于镍基高温合金 (2 0 0GPa)。随温度的升高其弹性模量下降 ,至90 0℃～ 10 0 0℃时为 15 0 GPa,接近于镍基高温合金值。如以 Ti Al取代钛基、镍基和铁基材料并以 Ti Al为基做成复合材料 (KM)可减轻零件质量 2 0 %～ 5 0 % ,与传统的耐热合金相比 ,Ti Al复合材料在空气中…     

用反应烧结和反应熔化法制取TiAl—TiB2复合材料

Ti Al基合金的优点是密度低、比强度高、刚度大、抗裂纹稳定性好 ,耐热可达90 0℃～ 10 0 0℃ ,Ti- Al的强力共价键可保证它有高的扩散激活能 ,从而能在 90 0℃以下阻止蠕变过程的发展。Ti Al的室温弹性模量为 16 0 GPa～ 175 GPa,高于一般钛合金(10 0 GPa) ,但低于镍基高温合金 (2 0 0GPa)。随温度的升高其弹性模量下降 ,至90 0℃～ 10 0 0℃时为 15 0 GPa,接近于镍基高温合金值。如以 Ti Al取代钛基、镍基和铁基材料并以 Ti Al为基做成复合材料 (KM)可减轻零件质量 2 0 %～ 5 0 % ,与传统的耐热合金相比 ,Ti Al复合材料在空气中…     

β-TiAl-xCr合金的相稳定性与力学性质预测

采用第一原理赝势平面波方法研究了Cr在B2-TiAl完整与缺陷晶体中的择优占位趋势,并基于虚拟晶体近似(VCA)与Born稳定性判据,计算了Cr合金化(浓度22.0%,原子分数,下同)完整与缺陷B2-TiAl晶体的弹性性质和Cr稳定β相的合金化浓度,进而采用Cauchy压力参数(c12-c44)、杨氏模量E、剪切模量G及其与体模量B的比值G/B表征和评判了Cr浓度对β-TiAl-x Cr多晶合金强韧化效果的影响。结果表明:B2-TiAl晶体的点缺陷结构主要为Ti反位,Cr在B2-TiAl完整与缺陷晶体中都优先占据Al原子位。在化学计量比β-Ti50Al50-xCrx合金与富Ti的β-Ti56Al44-xCrx合金中稳定β相的Cr合金化浓度分别为10%~15%和9%~20%。对于化学计量比β-Ti50Al50-xCrx(x=10~15)合金,Cr合金化可显著提高其强度与硬度,且浓度越高强化效果越好,但不存在明显的韧化效果;对于富Ti的β-Ti56Al44-xCrx(x=9~20)合金,合金塑性与韧性随Cr合金化浓度增加而变好,但Cr合金化的强化作用则不明显。     

CA-MIG热源处理下钛/铝异质合金界面显微组织特性

采用Al-Si5焊丝进行TC4钛/1060铝异质结构的CA-MIG连接,采用SEM、EDS等显微分析手段对不同热输入下所获接头的Ti/Al界面显微组织特点、界面附近元素分布进行分析,研究Ti/Al界面特性随热源热输入变化的演变规律。结果表明,CA-MIG热源热输入对Ti/Al界面显微组织具有显著影响。当热源热输入低于0.91 kJ/cm时,钛与铝基焊缝之间仅形成了一层界面反应层。当热源热输入处于0.91~1.55 kJ/cm时,钛与焊缝之间形成了两种Ti/Al界面,一种为单层结构的齿状Ti(Al,Si)₃;另一种由α-Ti(Al,Si)均匀层、Ti₅Si₃纳米颗粒+Ti(Al,Si)₃混合层、齿状Ti(Al,Si)₃层3层结构组成。当热源热输入超过1.55 kJ/cm后,除了上述两种Ti/Al界面外,局部微区钛合金发生熔化,与铝基焊缝之间形成了成分复杂的熔合区,熔合区内存在大量的裂纹缺陷。     

高Ti微合金高强钢静态再结晶动力学模型

采用Gleeble-3500热模拟试验机,通过应力松弛法对高Ti微合金高强钢的静态再结晶行为进行研究。结果表明:在高的变形(保温)温度和大的变形量下,静态再结晶进程加快,变形速率对静态再结晶的影响较小;计算出静态再结晶激活能Q_(rex)=276.45 kJ/mol,证实了微合金元素Ti有抑制再结晶的作用;基于Avarami方程确定了试验钢静态再结晶动力学模型。     

钛合金表面硬化与固体润滑处理层的电化学腐蚀行为研究

分别利用等离子氮化技术和离子束增强沉积(IBED)技术使钛合金表面获得硬质抗磨层和MoS2，MoS2-Ti固体润滑膜层。通过电化学测试技术研究了膜层和钛合金基材在含Cl^-介质中的抗蚀性能和接触腐蚀敏感性：研究结果表明：Ti与MoS2的复合改善了MoS2膜的环境适应性，MoS2—17Ti复合膜层与钛合会接触相容；IBED TiN较钛合金电化学活性低，阳极极化行为与Ti6Al4V合金相近，与钛合金基体间电偶腐蚀敏感性低；钛合金等离子氮化处理层在NaCl水溶液中无论处于自然腐蚀电位还上弱阳极极化状态，均较钛合金电化学活性低，且与钛合金基体间电偶腐蚀敏感性低。     

SiC纤维增强Ti/Ti_2AlNb叠层复合材料制备及界面行为研究

以SiC纤维、Ti箔、Ti_2AlNb箔为原材料,采用箔-纤维-箔方法,通过真空热压技术制备了SiCf/Ti/Ti_2AlNb叠层复合材料。利用扫描电子显微镜(SEM)、能谱分析仪(EDS)和X射线衍射仪(XRD)对复合材料相组成和微观组织进行了分析。结果表明,当真空热制造参数为920℃/40 MPa/30 min时,SiC纤维与韧性金属Ti实现良好冶金结合,界面反应产物主要为TiC,界面反应层厚度为0.8μm,C涂层厚度为1.3μm;韧性金属Ti层与金属间化合物Ti_2AlNb层通过Ti,Al,Nb 3种元素相互扩散方式形成固相扩散连接,界面平直,复合材料呈现出理想叠层结构。制备态的SiCf/Ti/Ti_2AlNb叠层复合材料主要由α-Ti,β-Ti,SiC,TiC,O相和B2相构成。在Ti与Ti_2AlNb固相扩散连接过程中,由于Al原子的扩散速率大于Nb原子,且Al是α稳定元素,Nb是β稳定元素,从而导致在Ti/Ti_2AlNb界面区域依次形成α+β双相组织和富B2相。在真空热压实验中,韧性金属Ti层与金属间化合物Ti_2AlNb层固相扩散连接过程依次为:物理接触/α+β双相区形成/富B2相区形成/富B2相区增厚。     

China's Major Non-ferrous Metals Imports & Exports

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Zinc Production by Province in 2014

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80% of Chinese Firms Purchasing Overseas Mines Ended up in the Red

<正>Minmetals Resources acquired the world’s largest copper mine under construction for USD5.85 billion.One after another,listed companies Jien Nickle,China Molybdenum and Chihong Zinc and Germanium raised money to get involved in overseas mining projects…SOEs and private enterprises are engaged in a frenzy of overseas mine purchasing.A reporter with Economic     

Copper Processing Profit Dropped Sharply,Copper Consumption Will Face Impact in the Second Half of the Year

正Judging from China’s copper consumption field,the biggest consumption unit is electric power,which accounts for 47%of total consumption;it is followed by light industry sector,including household electrical appliance,machinery,durable goods and hardware etc,which accounts for 22%of total consumption;followed by transportation field,     

Central Geological Prospecting Fund Newly Added 16.47 Million Tonnes of Bauxite in 2013

正In 2013,the Central Geological Prospecting Fund(CGPF)Project newly discovered 15 ore fields,including 3 large above ore fields,and 5medium sized ore fields.The reporter learned from the recently published"Annual Report of Central Geological Prospecting Fund Project(2013)"that,from 2006 to 2013 the CGPF     

Manufacturers of Copper Tube for Central Air Conditioner Use Face Mounting Pressure in the Final Quarter of the Year

正This year,the investment growth rate of real estate industry continued to slow down,sold area of commercial housing also dropped significantly,which brought huge pressure to the domestic air conditioning manufactures.In the first half of the year,by relying on high growth in national financial expenditure,along with investment in public infrastructure     

Xinjiang Ranks No.1 in Production of Primary Aluminum in China

正Kang Yi,Honorary Chairman of China Nonferrous Metals Industry Association,said recently at the Forum on Development of the Non-ferrous Metals Industry in Central and Western China held in Zhengzhou that,as more and more electrolytic aluminum factories in Xinjiang came into operation,the electrolytic aluminum output of Xinjiang had reached2,275,000 tons in the first 7 months this year,     

Shenhuo Coal Industry and Electricity Power Completed800,000 t/a Aluminum Project in Xinjiang

正"Xinjiang project has been completed according to schedule,but total completion and total start of production are two different concepts,after completion it still needs a gradual process of reaching production target."On the morning of November 3,Shenhuo Coal Industry and Electricity Power told investors the above statement on the investor interaction platform.     

Guangdong Metal Transaction Center has Become the Second Largest Precious Metal Transaction Platform Nationwide

正The reporter learned from Guangdong Province Precious Metal Transaction Center that in 2013the Center maintained healthy development momentum,and had become the second largest precious metal transaction platform in China in terms of market size;currently Guangdong is quickening steps of financial innovation for the Center,aiming to build a transaction center with international core competitiveness.     

Seven Rare Earth Projects Involving Close to 3 Billion Yuan Investment Landed In the HighTech Zone

正On May 22,Baotou Rare Earth Industry Cooperation Consultation MeetingProject Agreement-signing Ceremony was held in Ningbo,nearly 40 enterprises from Ningbo,Guangdong,Hunan,and Shanxi participated in project consultation.After multi-lateral communication,agreements were signed for a total of 7 rare earth projects successfully.