钛合金/碳纤维布复合材料的界面与力学性能的研究

本文选用Ti-6Al-4V钛合金为基体,镀铜碳纤维布为增强相来制备钛合金/碳纤维布复合材料。通过放电等离子烧结法(SPS)对镀铜碳纤维布与钛合金薄片进行叠层烧结,制备钛合金/碳纤维布叠层复合材料,并对其界面形貌、微观组织与力学性能进行表征。结果表明：镀铜碳纤维均匀分布在钛合金/碳纤维布复合材料中,CuTi, Cu和少量的TiC沿着纤维和基体的界面分布。钛合金/碳纤维布复合材料具有比钛合金略高的塑性,同时屈服强度和抗压强度与钛合金相比有了明显的提高。碳纤维表面电镀铜对复合材料界面有着重要的影响：(1)显着降低钛合金/碳纤维布复合材料的烧结温度;(2)提高了碳纤维和钛基体之间的润湿性,改善了界面结合,从而提高了钛合金/碳纤维布复合材料的力学性能;(3)有效地抑制TiC脆性相的产生,与未镀铜的碳纤布增强钛复合复合材料相比,镀铜碳纤维布/钛合金复合材料具有更好的塑性。     

钛合金/碳纤维布复合材料的界面与力学性能的研究（英文）

选用Ti-6Al-4V(TC4)钛合金为基体,镀铜碳纤维布为增强相来制备钛合金/碳纤维布复合材料。通过放电等离子烧结法(SPS)对镀铜碳纤维布与钛合金薄片进行叠层烧结,制备钛合金/碳纤维布叠层复合材料,并对其界面形貌、微观组织与力学性能进行表征。结果表明:镀铜碳纤维均匀分布在钛合金/碳纤维布复合材料中,Cu Ti,Cu和少量的TiC沿着纤维和基体的界面分布。钛合金/碳纤维布复合材料具有比钛合金略高的塑性,同时屈服强度和抗压强度与钛合金相比有了明显的提高。碳纤维表面电镀铜对复合材料界面有着重要的影响:(1)显着降低钛合金/碳纤维布复合材料的烧结温度;(2)提高了碳纤维和钛基体之间的润湿性,改善了界面结合,从而提高了钛合金/碳纤维布复合材料的力学性能;(3)有效地抑制TiC脆性相的产生,与未镀铜的碳纤布增强钛复合复合材料相比,镀铜碳纤维布/钛合金复合材料具有更好的塑性。     

热处理对激光增材制造Ti-5Al-2Sn-2Zr-4Mo-4Cr钛合金显微组织和力学性能的影响（英文）

研究热处理对激光增材制造Ti-5Al-2Sn-2Zr-4Mo-4Cr钛合金(TC17)的影响以优化其显微组织和力学性能。研究结果表明,激光增材制造TC17钛合金沉积态样品具有粗大的原始β柱状晶和等轴晶的混合晶粒形貌、晶内超细α片层和连续晶界α相(α_(GB))等典型特征。经α+β两相区840°C预处理和标准固溶时效热处理后,连续晶界α相(α_(GB))粗化并且在其两侧形成不含初生α相(α_P)的晶界无析出区(PFZ)。经单相区910°C预处理后,所有α相完全转变成β单相并且晶界附近溶质元素分布均匀,再经过标准固溶时效热处理形成明显断续的晶界α相(α_(GB))及呈均匀分布的晶内初生α相(α_P)和次生α相(α_S)。两种热处理工艺均可以明显提高激光增材制造TC17钛合金的综合力学性能,达到了TC17锻件航空标准规定值。     

真空退火处理对冷喷涂铝基复合材料组织与性能的影响

采用冷喷涂增材制造工艺制备了Al-25Al2O3、Al-50Al2O3和Al-75Al2O3(体积分数,％)具有不同体积含量Al2O3颗粒的铝基复合材料,并采用SEM、EBSD、硬度测试和拉伸测试等测试方法分析了真空退火处理对冷喷涂铝基复合材料的微观结构和力学性能的影响.结果表明,Al2O3颗粒的加入增加了冷喷涂增材材...     

退火工艺对增材制造TC18钛合金力学性能和组织的影响

采用显微组织观察和力学性能测试等方法研究了退火工艺参数对增材制造TC18钛合金力学性能和组织的影响。结果表明,增材制造TC18钛合金试块宏观形貌平整,表面没有裂纹等缺陷,表面呈均匀的银白色。试样经600 ℃退火保温2 h后的各项力学性能均满足GJB 2744A—2007指标要求,其规定塑性延伸强度为1036 MPa,抗拉强度为1084 MPa,断后伸长率为9.8%,断面收缩率为30%。增材制造TC18钛合金的组织为典型的柱状晶组织,粗大的β相柱状晶粒内为细长的针状α相及编织细密的α+β相板条组织;随着退火温度的升高,β相柱状晶内的针状α相逐渐粗化。     

Ti-6Al-4V丝材电弧增材制造钛合金的组织与性能

以Ti-6Al-4V丝材为原料,电弧为热源将钛合金丝材进行熔融,逐层堆积,用快速增材制造技术制备钛合金,并对合金的凝固过程、组织形貌和力学性能进行分析。结果表明,在丝材电弧增材制造过程中,开始堆积的1~2层为柱状晶,随后的堆积层则以等轴晶的方式生长。而且电弧的高热量输出,使得每个堆积区-熔合区-堆积区得到了有效的冶金结合,没有明显的界面和钛马氏体,各区域的显微组织均为稳定的α+β片层组织以及接近的显微硬度值。与铸态Ti-6Al-4V合金相比,电弧增材制造的钛合金不仅初始β晶粒细小,而且α+β片层间距也较小,其抗拉强度相比铸态提高3.6%,延伸率提高37%,拉伸断口为韧窝状的韧性断裂,与铸态合金存在一定撕裂棱的准解理断口形貌差异明显。     

激光增材制造高温合金复合材料研究进展

本文对增材制造技术在高温合金复合材料中的研究进行了系统全面地梳理归纳，综述了增材制造高温合金复合材料的粉末混合、冶金过程以及强化机制，并且在增材制造高温合金复合材料显微组织、缺陷及其性能方面进行详细对比分析研究。在此基础上，分析了增材制造高温合金复合材料研究现状及进展，并且对高温合金复合材料新增强相设计、增强相添加方式及其对蠕变疲劳性能的影响机制等的研究进行了展望，本文将有利于对增材制造高温合金复合材料的研究和发展提供参考。     

Co CrFeNi/6061Al复合材料冷喷摩擦复合增材制造及增强相影响规律研究

采用CoCrFeNi高熵合金颗粒代替传统陶瓷颗粒作为增强相,通过冷喷摩擦复合增材制造技术制备了CoCrFeNi/6061Al复合材料。采用SEM、EBSD、TEM和XRD检测技术对复合材料增材体的微观组织进行了表征,研究了不同CoCrFeNi颗粒体积分数对复合材料增材体微观组织和力学性能的影响。结果表明,冷喷摩擦复合增材制造消除了冷喷涂产生的大量微孔和微裂纹缺陷,实现了均匀致密CoCrFeNi/6061Al复合材料的增材制造。CoCrFeNi颗粒的加入使复合材料增材体晶粒显著细化。CoCrFeNi颗粒与Al基体发生界面反应生成的部分金属间化合物被机械破碎为纳米颗粒分散至Al基体内部。随着CoCrFeNi颗粒体积分数的增加,复合材料增材体的极限抗拉强度和平均显微硬度显著增加。     

Ti-6Al-4V线材电弧增材制造的组织与性能研究

本文采用Ti-6Al-4V线材为原料,以电弧为热源将钛合金丝材进行熔融,逐层进行堆积的快速增材制造,并对合金的凝固过程、组织形貌和力学性能等进行分析。结果表明,在丝材电弧增材制造过程中,在开始堆积的1~2层为柱状晶,随后的堆积则以等轴晶的方式生长。而且电弧高的热量输出,使得每个堆积区-熔合区-堆积区得到了有效的冶金结合,没有明显的界面和钛马氏体,各区域的显微组织均为稳定的α+β片层组织以及接近的显微硬度值。与铸态Ti-6Al-4V相比,电弧增材制造的钛合金不仅初始β晶粒细小,而且α+β片层间距也较小,其抗拉强度相比铸态提高3.6%,延伸率提高37%,拉伸断口为韧窝状的韧性断裂,与铸态合金存在一定撕裂棱的准解理断口形貌差异明显。     

搅拌摩擦通道挤压制备碳纳米管增强7075铝基复合材料

搅拌摩擦通道挤压是作者基于搅拌摩擦焊接和等通道转角挤压提出的一种固相状态制备金属基复合材料的新方法。采用搅拌摩擦通道挤压方法，通过添加不同体积分数的碳纳米管（CNTs）(0%、2%和4%)，制备了碳纳米管增强7075铝合金基复合材料（CNTs/Al-7075）。通过光学显微镜、扫描电子显微镜和透射电子显微镜观察并分析了CNTs在Al-7075基体中的分布特征，以及复合材料的细晶组织和第二相颗粒特征。采用固溶和时效处理改善CNTs/Al-7075复合材料的组织和力学性能。结果表明，采用搅拌摩擦通道挤压方法可以制备CNTs分布均匀的CNTs/Al-7075复合材料，实现7075铝合金基体晶粒细化，通过引入CNTs增强相可获得更为细小的晶粒组织。随着CNTs体积分数增加，CNTs/Al-7075复合材料的晶粒更加细化。固溶和时效处理改善了搅拌摩擦通道挤压制备的7075铝合金和CNTs/Al-7075复合材料的第二相析出行为，使材料的显微硬度得到提高。CNTs/Al-7075复合材料的强化机制综合了细晶强化、位错强化、载荷传递和第二相强化，其中以第二相强化为主。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.