中间钛片对TiB_2基陶瓷/钛合金梯度复合材料组织及性能的影响（英文）

在钛合金与陶瓷粉末之间引入厚度0.5~1.5mm的中间钛片,采用自蔓延离心熔铸工艺快速制备出了TiB_2基陶瓷/钛合金梯度复合材料。经过XRD、FESEM和EDS分析表明,添加钛片对陶瓷相没有明显的影响,但随着中间钛片厚度的增加,不仅细化陶瓷基体并改善其组织均匀性,而且增加了梯度界面厚度,减小甚至消除了钛合金基底热影响区。同时,热真空条件下液态陶瓷与钛合金之间发生熔化连接和原子互扩散,进而在凝固后期诱发TiB_2与Ti液的包晶反应TiB_2(s)+Ti(l)→2TiB(s),TiB自Ti液中的析晶反应和TiB与Ti液的共晶反应,实现了TiB_2的消减及TiB的生长,不仅改善了界面的残余应力,而且获得了陶瓷/钛合金多尺度多层次复合。界面组织结构的梯度演化与陶瓷/钛合金的热匹配不仅使梯度材料的硬度呈连续变化,而且使界面剪切强度达到了(316±25)MPa。     

Ti 元素对B4C/Al复合材料力学性能的改善作用研究

B₄C/Al复合材料是目前最理想的中子吸收材料,广泛用于乏燃料储存。本文利用液态搅拌法制备B₄C/Al复合材料,通过添加Ti元素,探讨了界面反应对材料的界面结构和力学性能的影响。研究发现,Ti元素通过参与界面反应,改变了界面结构,在B₄C颗粒表面形成了紧密结合的纳米TiB₂界面层;Ti的添加消除了界面微裂纹、微孔、分离等缺陷。随着界面反应程度的加强,材料强度提高,尤其反应脱落的纳米TiB₂颗粒作为原位第二强化相进一步增强基体。B₄C/Al复合材料断裂过程表现为韧窝延性断裂;TiB₂界面层增强了B₄C颗粒与基体的结合,断裂行为从B₄C-Al界面脱落转变为B₄C颗粒断裂;但过渡的界面反应会形成微韧窝,引起材料延伸率下降。     

超重力场反应加工TiB2基凝固陶瓷——Ti-6Al-4V多尺度多层次复合研究

采用超重力场反应加工技术,通过陶瓷-钛合金之间熔化连接与原子互扩散,制备出TiB2基凝固陶瓷—Ti-6Al-4V层状复合材料。XRD、FESEM及EDS分析发现,正是作为陶瓷基体相的TiB2片晶(或板晶)可诱发强烈的自增韧机制,使TiC-TiB2细晶凝固陶瓷具有高的弯曲强度与断裂韧性,并且也正是因在超重力场反应加工引发的热真空环境下钛合金与液态陶瓷发生熔化连接与原子互扩散,进而在凝固后期相继诱发TiB2与Ti液的包晶反应、TiB自钛液的析晶反应及TiB与钛液的共晶反应,最终实现以TiB2、TiB尺寸与分布为特征的陶瓷—钛合金多尺度(微米—亚微米—微纳米)多层次(TiC/TiB2—TiC1-x/TiB/TiB2—TiB2/Ti/TiC1-x/TiB—TiB2/TiC1-x/TiB/Ti—TiB/TiC1-x/Ti—TiC1-x/Ti—Ti)复合。     

Ti活度对Al2O3/AgCuTi/Fe-Ni-Co钎焊接头机械性能和微观组织结构的影响

采用AgCuTi钎料实现了Al₂O₃陶瓷与Fe-Co-Ni合金的钎焊连接,并调查了不同钛含量的钎料对Al₂O₃/AgCuTi/Fe-Ni-Co钎焊接头机械性能和微观组织结构的影响。扫描电子显微镜(SEM), X射线能量色散光谱仪(EDS), X射线衍射仪(XRD)及电子万能试验机用于分析钎焊接头的机械性能和微观组织结构,结果表明:钛含量的增加明显提高AgCuTi钎料与Al₂O₃陶瓷的相互作用,在Al₂O₃/Ag-Cu-Ti界面生成一层由Ti-Al 和 Ti-O化合物组成的反应层。Al₂O₃/AgCuTi/Fe-Ni-Co钎焊接头的抗拉强度随钛含量的增加而增加,当钛含量提高到8wt.%时,抗拉强度达到最大值78Mpa。通过微观组织结构分析发现,采用AgCu4Ti在890℃保温5min的条件下可以获得较好的钎焊接头,典型接头的微观组织结构为Al₂O₃/TiAl+Ti₃O₅/NiTi+Cu₃Ti+Ag(s,s)/Ag(s,s)+Cu(s,s)+(Cu,Ni)/Fe-Ni-Co。采用AgCu8Ti获得的钎焊接头的界面反应层与AgCu4Ti差异不大,但反应层稍微增厚,并伴有TiO和Ti3Al在Al₂O₃/Ag-Cu-Ti界面生成。     

超重力场反应加工TiB2基陶瓷与钛合金复合的研究

采用超重力场反应加工技术,通过陶瓷-钛合金之间熔化连接与原子互扩散,成功制备出TiB2基凝固陶瓷-Ti-6Al-4V层状复合材料。经XRD、FESEM及EDS分析发现,正是作为陶瓷基体相的TiB2片晶(或板晶)可诱发强烈的自增韧机制,使TiC-TiB2细晶凝固陶瓷具有高的弯曲强度与断裂韧度,并且是在超重力场反应加工引发的热真空环境下钛合金与液态陶瓷的熔化连接与原子互扩散,进而在凝固后期诱发TiB2与Ti液的包晶反应、TiB自钛液的析晶反应及TiB与钛液的共晶反应,最终实现以TiB尺寸、分布为特征的陶瓷-钛合金多尺度(微米-亚微米-微纳米)多层次(TiC/TiB2-TiC1-x/TiB/TiB2-TiB2/Ti/TiC1-x/TiB-TiB2/TiC1-x/TiB/Ti-TiB/TiC1-x/Ti-TiC1-x/Ti-Ti)复合。     

W含量对自蔓延离心熔铸TiB2-TiC-(Ti,W)C陶瓷组织性能的影响

通过在(Ti+B₄C)体系中引入(WO₃+Al)燃烧体系,进而调整两体系的比例,采用自蔓延离心熔铸工艺成功制备出W系列含量的TiB₂-TiC-(Ti, W)C复合陶瓷。XRD、FESEM和XRD结果显示：陶瓷基体主要由TiB₂、TiC和(Ti, W)C固溶体组成,且随着W含量的增加,(Ti, W)C固溶体体积分数增加,而TiB₂和TiC体积分数减少且晶粒逐渐细化,同时,组织分布趋于均匀。力学性能测试表明,随着W含量的增加,TiB₂-TiC-(Ti, W)C复合陶瓷的相对密度和维氏硬度呈上升趋势,而陶瓷的弯曲强度和断裂韧性先增大后减小,在W含量65%时达到最大值,这是TiB₂作为唯一的增强相体积分数逐渐减少的结果。     

过渡元素改善B4C/Al材料界面润湿性的机理研究

B₄C/Al复合材料是目前最理想的中子吸收材料,但工业上常用的液态搅拌法制备过程中存在着界面润湿性差的问题。本文结合实验及第一性原理的方法,通过研究Al(111)/AlB₂(0001)和Al(111)/TiB₂(0001)界面的结构来分析工业上添加过渡元素Ti对B₄C/Al界面润湿性的改善机制。通过计算发现,Al(111)/TiB₂(0001)界面相对Al(111)/AlB₂(0001)界面具有更高的粘附功值,说明其界面结合更强。进一步对比Ti掺杂二硼化物和AlB₂的偏态密度结构,发现Ti掺杂体具有较低的反键态,表明Ti-3d和B-2p轨道电子杂化后,在B、Ti原子间形成了较强的化学键,从而促进了Al(111)/TiB₂(0001)界面处的强结合作用,提高了Al(111)/TiB₂(0001)界面粘附功,故而改善了B₄C/Al界面的润湿性。根据同样的理论依据,V掺杂体也具有较低的反键态,V和B之间的强结合效果或许能够改善B₄C/Al界面的润湿性,成为又一理想的溶体改性掺杂元素。     

钛合金表面TiB2涂层与纯铝的高温黏着磨损行为*

航空发动机低压气机机匣内表面 Al 基封严涂层的使用,可以通过其自身的磨耗实现保护 TC4 叶尖的目的,但同时 Al 基封严涂层中以 Al 为主的基体材料易于大量黏着转移至 TC4 叶尖表面,使叶尖长度增加,影响发动机运行稳定性。采用直流脉冲磁控溅射工艺在钛合金表面沉积 TiB₂ 涂层,以期实现抗 Al 黏着磨损目的。具有致密结构的 TiB₂涂层在钛合金表面膜基结合临界载荷(L_C4)达 85.4 N。在高温销-盘摩擦磨损试验机上评价钛合金表面 TiB₂涂层与纯铝销对摩(室温至 450 ℃) 的抗 Al 黏着磨损性能。与 TC4 基体相比较,TiB₂ 涂层可有效抑制 Al 的黏着转移。对摩铝销磨斑具有拖尾特征和剪切舌特征。 铝销向 TiB₂涂层表面的机械涂抹和铝销对 Al 黏着转移层的剪切去除作用相互竞争,共同控制 Al 的黏着转移行为。TiB₂涂层磨痕内保持低表面粗糙度可减小高温软化铝销的机械涂抹倾向。同时 TiB₂涂层与 Al 黏着转移层间优异的化学稳定性可阻碍界面反应进行,降低界面结合强度,进而促进铝销对 Al 黏着转移层的剪切去除作用。钛合金表面 TiB₂ 涂层通过抑制铝销机械涂抹并增强铝销对 Al 黏着转移层的剪切去除而获得优异的抗 Al 黏着磨损性能。     

钛/铝/钛层状复合材料的爆炸复合制备及后续热压处理研究

本文以纯钛板与纯铝板为原料,通过爆炸复合法制备钛/铝/钛层状复合材料,之后采用热处理以及热压工艺对钛/铝/钛层状复合材料进行进一步处理。研究结果表明：复合板界面主要由波状界面和平直状界面构成,铝元素与钛元素在界面上发生了互扩散,界面结合性能优良,可以承受后续较大的二次塑性变形;热处理后的复合板界面发生明显扩散,在热处理25 h后热压2.5 h后铝层完全反应,扩散反应层主要由TiAl₃相以及Ti₂Al₅相构成。     

TiB2基陶瓷/Ti-6Al-4V合金梯度纳米结构复合材料组织演化与防弹性能

基于陶瓷/钛合金液态熔合与扩散原理,采用离心反应熔铸工艺成功制备出TiB2基陶瓷/Ti-6Al-4V梯度纳米结构复合材料。经14.5 mm军用制式穿甲弹DOP靶试,TiB2基陶瓷与TiB2基陶瓷/Ti-6Al-4V梯度纳米结构复合材料的平均质量效益分别为3.05和7.30,因此可认为由于陶瓷/钛合金层间生成TiB2、TiB呈空间尺度连续梯度演化的复合结构,该复合材料不仅具有高的层间解离抗力与优异的整体力学性能,而且通过层间载荷传递与多尺度（微米/微纳米/纳米）界面剪切耦合的双重效应,又在靶试中表现出高的抗弹性能。     

TiC-TiB2陶瓷与Ti6Al4V熔化连接及层状复合材料制备

通过引入Ti-6Al-4V合金板,采用超重力场燃烧合成技术,在制备细晶TiC-TiB2凝固陶瓷的同时,实现了陶瓷-钛合金的熔化扩散焊,进而制备出具有成分梯度特征的陶瓷-钛合金层状复合材料.陶瓷-钛合金层间接头组织表明,正是因超重力场燃烧合成的爆燃特性及超重力场对燃烧产物形成的高温真空环境,使得钛合金表面发生熔化,进而发生液态陶瓷-钛合金液相层间的原子互扩散现象,故在陶瓷-钛合金连接区形成钛合金与富钛碳化物呈相间分布且细小TiB2片晶镶嵌其上的凝固组织,并使陶瓷-钛合金接头呈现成分梯度特征,进而使得陶瓷-钛合金的连接抗剪强度达到450 MPa±35 MPa,层状复合材料硬度从陶瓷至钛合金一侧则呈线性逐渐减小.     

Invar合金与Si_3N_4陶瓷钎焊接头界面组织和性能研究

采用Ag Cu Ti活性钎料对Invar合金和Si3N4陶瓷进行钎焊连接,研究了接头界面组织及其形成机制,分析了钎焊工艺参数对接头界面结构和性能的影响。结果表明,钎焊过程中液态钎料中的活性元素Ti与Si3N4陶瓷发生反应,在陶瓷界面形成致密的Ti N和Ti5Si3反应层;同时,Invar合金向液态钎料中溶解,与活性元素Ti反应生成脆性的Fe2Ti和Ni3Ti化合物。钎焊温度和保温时间影响Si3N4陶瓷界面反应层的厚度以及接头中Fe2Ti和Ni3Ti脆性化合物的形成量和分布,这两方面共同决定着接头的抗剪强度。当钎焊温度为870℃,保温15 min时,接头的平均抗剪强度最大值达到92.8 MPa,此时接头的断裂形式呈现沿Si3N4陶瓷基体和界面反应层的复合断裂模式。     

超高重力场燃烧合成TiB2基陶/304不锈钢叠层复合材料

采用超高重力场燃烧合成技术,通过陶瓷和不锈钢之间的熔化连接与原子互扩散,制备出界面具有化学成分梯度特征的TiB2基陶瓷/1Cr18Ni9Ti不锈钢复合材料。因超高重力场燃烧合成工艺具有“爆燃”的特性以及超高重力场所形成的高温真空环境,使得不锈钢表面发生部分熔化,进而实现了陶瓷/不锈钢的熔化连接。经XRD、FESEM 及EDS 分析发现,接头界面连接良好,并因原子的强烈互扩散在界面过渡区形成了三维网络陶瓷/金属梯度复合结构。经测试发现,维氏硬度值与陶瓷基体至不锈钢基底测试距离的关系曲线呈近似抛物特征。同时,复合材料的界面剪切强度达到325±25 MPa,其界面断裂模式是由TiB2片晶沿晶断裂和Fe-Ni-Cr合金相延性断裂的混合模式组成。     

Cu + TiB2 composite filler for brazing Al2O3 and Ti-6Al-4V alloy

Al₂O₃ and Ti-6Al-4V alloy were brazed using Cu + TiB₂ composite filler, which manufactured by mechanical milling of Cu and TiB₂ powders. Typical interface microstructure of joint was Al₂O₃/Ti₄(Cu,Al)₂O/Ti₂Cu + Ti₃Al + Ti₂(Cu,Al)/Ti₂(Cu,Al) + AlCu₂Ti/Ti₂Cu + AlCu₂Ti + Ti₃Al + Ti₂(Cu,Al) + TiB/Ti(s.s) + Ti₂Cu/Ti-6Al-4V alloy. Based on temperature- and time-dependent compositional change, the formation of intermetallics in joint was basically divided into four stages: formation of interfacial Ti₄(Cu,Al)₂O in Al₂O₃ side, formation of Ti₂Cu, Ti₃Al, TiB, Ti₂Cu, and AlCu₂Ti in layers II and IV, formation of Ti₂(Cu,Al) and AlCu₂Ti in layer III, formation of Ti + Ti₂Cu hypereutectoid organization adjacent to Ti-6Al-4V alloy. TiB in situ synthesized in joint not only acted as low thermal expansion coefficient reinforcement to improve the mechanical properties at room temperature, but also as skeleton ceramic of joint to increase high temperature mechanical properties of Al₂O₃/Ti-6Al-4V alloy joint increasing. When the joint containing 30 vol.% TiB brazed at 930 °C and 10 min of holding time, the maximum room temperature shear strength of joint was 96.76 MPa, and the high temperature shear strength of joint was 115.16 MPa at 800 °C.     

Joining of ZrB2 Ceramics to Ti6Al4V by Ni-Based Interlayers

Pure ZrB₂ and ZrB₂-SiC composites were joined to Ti6Al4V at 1100 °C using B-Ni50 (at.%) as a filler alloy. The brazing medium and the processing parameters were chosen on the basis of specific wetting tests which showed the good adhesion properties of the B-Ni alloy with both the ceramic and the Ti alloy; interfacial reactions were foreseen and interpreted by phase diagram analysis. A multilayer metal-ceramic interfacial structure was observed in the joints and a key role was played by Ti coming from Ti6Al4V: it worked as the active element enhancing the adhesion of the liquid to the ceramic and segregated at the interface forming TiB. A satisfactory mechanical performance was obtained for ZrB₂-SiC/Ti6Al4V joints, which exhibited a room temperature shear strength of 74 MPa.     

Microstructure and properties of TiB/Ti-6Al-4V coatings produced with laser treatments

TiB/Ti-6Al-4V metal-matrix composite (MMC) layers were produced on Ti-6Al-4V substrates by laser cladding. A TiB₂/Ti powder mixture was used as a precursor to obtain a dispersion of TiB needles in the Ti alloy matrix, with the aid of an exothermic reaction between TiB₂ and Ti. A eutectic microstructure was obtained that consisted of an extremely homogeneous dispersion of TiB eutectic needles in the Ti alloy matrix, having a volume fraction as high as 0.33. Also, an equilibrium-like microstructure was found, consisting of a dispersion of both primary and eutectic TiB needles inside the Ti alloy matrix. An analysis of the geometry of the layers was performed and proved successful in determining the percentage of B. Further, it correctly predicted the variation of atomic B content as a function of laser power. The relative wear resistance coefficient, defined as the wear coefficient of the uncoated matrix divided by that of coating, shows an improvement by a factor as high as 1500 for the eutectic microstructure. This paper was presented at the 2nd International Surface Engineering Congress sponsored by ASM International, on September 15–17, 2003, in Indianapolis, Indiana, and appeared on pp. 411–18 of the Proceedings.     

Behaviors of interfacial elements during the brazing of SiO2 glass ceramic to Ti-6Al-4V with AgCu/Ni interlayer

AgCu/Ni composite interlayer was used to join SiO₂ glass ceramic to Ti-6Al-4V alloy successfully, obtaining the largest joint shear strength 110MPa. Ag, Cu and Ni in the interlayer and Ti in the Ti-6Al-4V alloy affect the joint formation and interfacial products significantly. To understand the joint formation process better, behaviors of elements Ag, Cu, Ni and Ti during the brazing of SiO₂ glass ceramic to Ti-6Al-4V alloy were investigated in the present work. Active element Ti is the most important component in the joining, realizing the metallurgical bonding of SiO₂ glass ceramic to braze alloy. Cu together with Ni reacts to Ti in the base material by Ti-Cu-Ni ternary eutectic reaction, which is beneficial for reducing the massive Ti-Cu and/or Ti-Ni brittle intermetallic compounds on the joint interface. Dispersion of Ag decreases the brittleness of the whole joint effectively.     

In Situ Synthesis of Ceramic Reinforcements for Carbon/CuCrZr Joints Brazed with Composite Fillers

Brazing of two kinds of carbon materials including graphite and carbon fiber-reinforced carbon composites to copper alloys has been realized with CuTiH₂ + BN composite fillers. The microstructure characterization reveals that the ceramic reinforcements containing TiN particles and TiB whiskers have been synthesized by in situ reaction of BN additives with Ti discomposed from TiH₂ in the composite filler. The filler layer of the joints is mainly composed of Cu-based solid solutions [Cu (ss)] and Ti-Cu intermetallics along with ceramic reinforcements. Furthermore, a continuous thin reaction layer mainly containing TiC is developed at the interface close to the carbon substrates. The growth of TiC layer is mainly controlled by the diffusion of carbon from the substrates into the liquid filler through the TiC layer formed. The interface evolution of the graphite/CuCrZr joints has been discussed. The electrical resistivity of the joining area is relatively low, which highly meets the requirement for the carbon commutator applications.