Ti对Mo-Ti合金拉伸强度及显微组织的影响

采用粉末冶金方法制备Mo-Ti合金,研究合金元素添加方式及添加量对材料拉伸强度和显微组织的影响。结果表明,添加Ti112粉末所制备的合金的拉伸强度及相对密度均较添加纯Ti粉末的合金高,当添加量（质量分数）为0．8％时合金拉伸强度最高。显微组织分析结果表明,一部分Ti固溶到Mo基体,提高材料的拉伸强度,另一部分则与Mo及合金中的氧结合形成MoxTiyOz复合氧化物第二相粒子,起到细化晶粒及净化晶界的作用。     

微量合金元素Ti、Zr对Mo金性能和显微组织的影响

采用粉末冶金法制备Mo-Zr、Mo-Ti合金,研究了Zr、Ti的添加方式及添加量对Mo的拉伸性能和显微组织的影响。结果表明,添加合金元素Zr、Ti大大提高了Mo的力学性能。合金元素Zr以纯Zr形式加入较以ZrH2形式为佳,其添加量在0.1%（质量分数,下同）时,合金性能最高。元素Zr仅有极少部分固溶到Mo基体中,大部分与合金中少量氧结合以ZrO2粒子相存在。合金元素Ti则以TiH2的方式添加为佳,添加量为0.8%时合金性能最高。元素Ti一部分固溶到Mo基体中,另一部分与Mo及合金中的少量氧结合以MoxTiyOz复合氧化物粒子相存在。     

微量合金元素Ti、Zr对Mo合金性能和显微组织的影响

采用粉末冶金法制备Mo-Zr、Mo-Ti合金,研究了Zr、Ti的添加方式及添加量对Mo的拉伸性能和显微组织的影响.结果表明,添加合金元素Zr、Ti大大提高了Mo的力学性能.合金元素Zr以纯Zr形式加入较以ZrH2形式为佳,其添加量在0.1%(质量分数,下同)时,合金性能最高.元素Zr仅有极少部分固溶到Mo基体中,大部分与合金中少量氧结合以ZrO2粒子相存在.合金元素Ti则以TiH2的方式添加为佳,添加量为0.8%时合金性能最高.元素Ti一部分固溶到Mo基体中,另一部分与Mo及合金中的少量氧结合以MoxTiO2复合氧化物粒子相存在.     

梯度掺杂和纳米多层调制类金刚石薄膜的摩擦学性能

采用阴极电弧结合离子源辅助磁控溅射复合技术,充分利用薄膜组成多元化、晶体纳米化、组成和结构多层化、梯度化的优势,分别制备了多元素复合过渡层缓冲的钨元素梯度掺杂的和Cr元素纳米多层调制的类金刚石(DLC)薄膜,研究掺杂元素含量和调制层厚度对薄膜组成与结构、力学性能和摩擦磨损性能的影响。梯度掺杂、多元、多层结构降低了DLC膜和钢基体之间因组成和结构不同产生的应力,改善了膜基结合力,材料综合耐磨损性能大幅度提高。     

铸渗表面耐磨复合层的研究

运用铸渗理论，通过控制渗剂材料的组成，在铸钢件表面形成了一层耐磨复合层。研究结果表明，该复合层中的合金元素呈梯度分布，其组织中含有大量的小块状、菊花状（Ｆｅ，Ｃｒ７）Ｃ３和弥散分布的细小石墨颗粒，在不同载荷的干滑动摩擦条件下，该复合层大大改善了铸钢件的表面耐磨性     

渗硅制备Mo-MoSi_2梯度材料层的特性

以Mo为基体,利用KCl-NaCl-NaF-(SiO2)熔盐体系电沉积出的硅作为渗硅硅源,电沉积硅和在Mo基体上渗硅同时进行,制备Mo-MoSi2梯度材料.以实验结果和理论计算为依据,对梯度层的特性进行了分析.结果表明:梯度层硅含量呈3种不同的变化规律,在靠近试样表面部分,硅含量沿深度下降率较大,在梯度层中间部分,硅含量基本保持不变,在梯度层靠近Mo一侧.硅含量的下降率介于前两者之间;梯度层中,以Mo、Mo3Si、Mo5Si3 3种物质构成的厚度占整个梯度层的比重最大;梯度层沿Mo基体一侧向表面的物质组成变化规律为:Mo→Mo5Si3+Mo3Si+Mo→Mo5Si3+MoSi2→MoSi2,并且各物质所占的比重随硅含量的变化而变化.     

Mo-MoSi_2功能梯度材料的三点弯曲行为

采用渗硅工艺制备了Mo-MoSi2功能梯度材料,并利用扫描电镜、X射线衍射以及弯曲强度试验观察并分析Mo-MoSi2功能梯度材料的微观结构和断裂行为。结果表明,梯度材料由表及里的结构变化形式为表层MoSi2晶粒(尺寸为6.8μm)+少量Si→MoSi2柱状晶粒(长度为15μm)→过渡层(2μm)→Mo基体。该Mo-MoSi2功能梯度材料具有组织致密,MoSi2晶粒细小,梯度层与Mo基体界面结合良好等特点。Mo-MoSi2梯度材料具有良好的弯曲性能,弯曲强度为1025 MPa,断裂挠度为1.87 mm,弹性模量为26.6 GPa。在保证Mo基体强度的同时,MoSi2功能梯度涂层显著提高了Mo基体塑性性能。Mo-MoSi2梯度材料的弯曲断裂形式主要为沿晶断裂和穿晶断裂两种形式。过渡层和MoSi2涂层形成是Mo-MoSi2功能梯度材料断裂韧性提高的主要原因。     

304 不锈钢表面 Mo 合金化改性层组织结构及耐磨性研究

目的提高304不锈钢表面耐磨性能。方法利用双辉等离子合金化技术,使304不锈钢表面形成Mo合金化渗层。分析渗层的成分分布和相结构,对比基体材料和Mo合金化改性层的硬度、磨痕形貌和摩擦磨损性能。结果所制备的Mo合金化渗层均匀致密,厚9.6μm,主要由纯Mo相构成。合金化元素Mo在渗层中从基体表面到内部呈梯度分布,表面显微硬度值达806HV0.05。在干摩擦条件下,Mo合金化渗层的比磨损率仅为304不锈钢基体的1/84,使材料的抗磨损性能得到明显改善。结论双辉等离子Mo合金化能够有效改善304不锈钢的抗磨损性能。     

等离子W、Mo、Y共渗层的组织研究

研究了Y元素对等离子W、Mo、Y共渗渗层的晶粒大小、厚度和渗层中W、Mo原子扩散系数的影响。研究发现,偏聚在晶界上的Y原子和少量金属间化合物Fe17Y2阻碍了渗层晶粒的长大,细化了渗层的晶粒。从扩散热力学角度,探究了Y元素对渗层厚度的影响。Y元素降低了表面W、Mo原子的活度,表面W、Mo原子的化学势降低,进而使表面与基体之间的化学梯度减小,W、Mo原子的扩散速率减慢,渗层厚度变薄。通过Fick第二扩散定律计算渗层中不同位置、浓度下的W、Mo原子扩散系数,结果表明W、Mo原子的扩散系数在10-13～10-14之间。     

W-Mo-Y等离子共渗合金层的研究

研究Q235钢表面等离子W-Mo-Y共渗层的组织、成分、结构、显微硬度,计算渗层中不同位置、浓度下的W、Mo原子扩散系数。结果表明：渗层组织为柱状晶,W、Mo元素呈梯度分布,Y的分布不均匀。共渗层主要结构相为钨钼在α-Fe中的固溶体和Fe17Y2,共渗层显微硬度最高256 HV0.05;Y元素降低表面W、Mo的活度,W、Mo合金元素的化学势变小,表面与基体之间的化学梯度减小,W、Mo原子扩散速率减慢;W-Mo-Y共渗层厚度要比W-Mo共渗层厚度薄;通过Fick第二扩散定律计算表明,在W-Mo-Y共渗和W-Mo共渗时,不同渗层中的W、Mo扩散系数有所不同,但属同一数量级即：10-13～10-14之间。     

Influence of TiC Addition on Properties and Microstructure of Mo-Ti AlloyEI北大核心

Mo-Ti-TiC alloys were fabricated by powder metallurgy process through adding TiH2 powder and ultrafine TiC powder into Mo metal. The influence of the addition of nano-scale TIC particles on the microstructure and tensile properties of Mo-Ti alloy was studied. The results indicate that the tensile strength of Mo-Ti alloy was effectively increased by TiC particles addition. Mo-Ti with 0.05wt% TiC exhibited the highest tensile strength, which is 31.7% higher than that of Mo-Ti alloy. The addition of TiC protects Ti from oxidation, which is produced by decomposition and dehydrogenization of TiH2 particles. The second phase particles containing Mo, Ti, 0 and C in the alloy were formed with TiC addition. The grain size of the alloy decreased with the increase of the TIC content since the second phase particles can inhibit the grain growth.     

TiC的添加对Mo-Ti合金性能与组织结构的影响

采用粉末冶金法,通过在金属Mo中添加TiH2粉末及超细TiC粉末制备Mo-Ti-TiC合金,研究TiC的添加对Mo-Ti合金的拉伸性能和显微组织的影响.结果表明,TiC的添加使Mo-Ti合金的拉伸强度得到有效提高.TiC添加量在0.05%(质量分数)时,合金拉伸强度最高,强度较Mp-Ti合金提高了31.7%.TiC的添加保护了基体中由TiH2颗粒分解脱氢所形成的单质Ti颗粒,降低其氧化程度.添加TiC后,合金内部生成含元素Mp、Ti、O和C的第二相粒子,有效阻止合金晶粒长大,因此,随着合金中TiC含量的增加,合金的晶粒尺寸减小.     

Investigation on gradient material fabrication with electron beam melting based on scanning track control

A new electron beam control system was developed in a general vacuum electron beam machine by assembling with industrial control computer, programmable logic control （PLC）, deflection coil, data acquisition card, power amplifier, etc. In this control system, scanning track and energy distribution of electron beam could be edited off-line, real-time adjusted and controlled on-line. Ti-Mo gradient material （GM） with high temperature resistant was fabricated using the technology of electron beam melting. The melting processes include three steps, such as preheating, melting, and homogenizing. The results show that the GM prepared by melting technology has fine appearance, and it has good integrated interface with the Ti alloy. Mo and Ti elements are gradually distributed in the inter.face of the gradient material. The microstructure close to the Ti alloy base metal is α ＋ β basket-waver grain, and the microstructure close to the GM is a single phase of β solid solution.     

Fabrication of Mo-Ti functionally graded material

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Corrosion resistant Ti alloy for sulphuric acid medium: Suitability of Ti–Mo alloys

The corrosion resistance of Ti–Mo (5, 10, 15 and 25 wt% molybdenum) alloys in 5–25% sulphuric acid was evaluated. The Ti–Mo alloys offered a better corrosion resistance than commercially pure titanium (CP‐Ti). The higher impedance values, higher phase angle maximum, ability to reach the phase angle maximum at relatively lower frequencies, ability to exhibit a constant phase angle maximum over a wider range of frequencies, higher phase angle values at 0.01 Hz, have confirmed the formation of a stable passive oxide film on Ti–Mo alloys. The study recommends the use of Ti–Mo alloys, particularly Ti–25Mo alloy, as a suitable material of construction for sulphuric acid medium.     

箔-纤维-箔法制备Mof/TiAl复合材料的显微组织与性能

利用箔-纤维-箔法和热压烧结成功制备出Mo_f/Ti48Al复合材料,并分析了Mo纤维对TiAl合金显微组织和力学性能的影响。结果表明,通过635 ℃,3 MPa,10 h+680 ℃,3 MPa,4 h的两步低温热压,箔材中的Al完全反应完,TiAl箔叠层材料形成致密的Ti/TiAl₃板材,合金致密基本无孔洞。再通过1200 ℃,36 h的高温退火,Ti与TiAl₃在高温下继续反应,形成γ-TiAl、α-Ti₃Al相。高温退火后的钼纤维与基体合金发生了扩散反应,形成了扩散区域,此区域内主要相组成为TiMo、AlMo₃,钼纤维与基体合金通过扩散紧密结合在一起,界面未发现孔洞和因应力形成的裂纹。相比于未添加钼纤维的合金,添加10vol%钼纤维的复合材料抗弯性能有明显的提高,钼纤维在合金中起到了强韧化作用。     

高钼含量TB8钛合金新型VAR熔炼工艺

研究了高钼含量TB8钛合金新型VAR熔炼工艺,采用工业纯钼粉直接加入的工艺方法熔炼生产TB8钛合金铸锭,通过选用合适的原材料和合理的VAR工艺参数,成功的生产出TB8钛合金铸锭。经过不同部位成分分析、低倍金相观察、X射线试验,证明其成分均匀且不存在高熔点、高密度钼组元等夹杂、偏析缺陷。该新型工艺的原料成本、质量成本、生产成本都大幅低于传统工艺。     

Solidification structure in a cast γ alloy

Solidification microstructure of a cast Ti–50Al–6Mo alloy has been examined. The as-cast microstructure consists of β-dendrites, lamellar α₂+γ regions, eutectoid β+γ and a thin γ layer at the interface between β dendrite and lamellar structure. The microscopic basis of crystallographic texture present in the material as a consequence of the solidification path in the alloy Ti–50Al–6Mo, which solidifies through a L+β phase field has presented.     

Localized corrosion properties of low interstitial ferritic,high purity austenitic and high chromium duplex stainless steels

Within the framework of a research aimed at characterizing the behaviour of new materials to pitting and crevice corrosion, an investigation has been made, using electrochemical techniques, of the following materials: ELI ferritic stainless steels (18 Cr-2 Mo-Ti; 21 Cr-3 Mo-Ti; 26 Cr-1 Mo); high chromium duplex stainless steel (Z 5 CNDU 21-08) and high chromium-nickel austenitic stainless steel (Z 2 CNDU 25-20); commercial austenitic stainless steels (AISI 304 L and 316 L) and laboratory heats of austenitic stainless steels with low contents of interstitials (LTM/18 Cr- 12 Ni, LTM/16 Cr- 14 Ni-2 Mo). It was possible to graduate a scale of resistance to pitting and crevice corrosion in neutral chloride solutions at 40 C; in particular the two experimental austenitic stainless steels LTM/18 Cr- 12 Ni and LTM/16 Cr- 14 Ni-2 Mo are at the same level as the AISI 316 L and 18 Cr-2 Mo-Ti, respectively. An occluded cell was developed and used for determining the critical potential for crevice corrosion (E_{localized corrosion}). For the steels under investigation E_{localized corrosion} is less noble than E_pitting especially for ELI ferritic 18 Cr-2 Mo-Ti and 21 Cr–3 Mo-Ti.     

Preparation of Ti-Mo system functionally graded materials by co-sedimentation

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