烧结工艺对微波烧结TiC/2024复合材料组织和性能的影响

为了获得微波烧结TiC/2024铝基复合材料较为理想的组织与性能,本文对高Ti C添加量的2024铝合金进行烧结,运用扫描电子显微镜,对热处理前后试样进行金相显微组织的观察,并对烧结后的试样进行显微硬度测试。结果表明,经过540℃固溶保温1.5 h,160℃时效保温8 h工艺处理的材料有较好的综合力学性能。     

热处理工艺对微波烧结TiC/6061复合材料组织和性能的影响

为了获得微波烧结TiC增强6061铝基复合材料较为理想的热处理工艺,运用扫描镜对热处理前后试样进行金相显微组织观察,并对热处理后的试样进行显微硬度测试。结果表明,经固溶温度540℃保温1.5h,时效温度160℃保温8 h工艺处理的材料有较好的综合力学性能。     

微波烧结温度对TiC/6061铝基复合材料的影响

通过微波烧结法制备了6061铝合金和20TiC/6061铝基复合材料,研究了烧结温度对材料组织和性能的影响。结果表明,通过微波烧结法制备的6061铝合金,随着烧结温度升高,冶金结合程度提高,组织和性能也更好。在试验烧结温度范围内,致密度最终基本稳定在96%左右;当烧结温度为560℃时,TiC/6061铝基复合材料,增强相尺寸细小且分布较均匀,基体致密、结合良好。XRD物相分析显示,6061铝合金中只有Al相存在,复合材料中只有基体相Al和增强相TiC,未生成其他相。     

TiC含量对高温钛基复合材料组织与性能的影响

通过真空非自耗熔炼工艺制备了不同TiC含量(1,2.5,5,7.5,10,15vol.%)的近α高温钛合金基复合材料。采用X射线衍射仪(XRD)、金相显微镜(OM)、扫描电镜(SEM)和万能材料试验机,系统研究了TiC_p含量对近α高温钛合金基复合材料显微组织和力学性能的影响规律。研究结果表明,可以利用Ti与C之间的原位反应制备TiC/Ti复合材料,随着TiC含量的升高,TiC的形态逐渐由长条状向等轴状、枝晶状发展,其不同的形态主要是由其凝固路径决定的。室温压缩性能表明,随着TiC含量的升高,抗压强度和屈服强度明显升高,但达到一定值后强度有不同程度的降低,而压缩率随着TiC含量的升高明显降低。     

TiC含量对微波烧结钢结硬质合金组织及性能影响

以铁粉为基体,TiC颗粒为增强相,通过球磨、压制成型,微波烧结制备出TiC钢结硬质合金。结果表明,在1400℃微波烧结时,TiC颗粒与Fe具有良好的润湿性和流动性。随TiC含量升高,合金的晶粒逐渐变得均匀细小,合金的相对密度、显微硬度和抗弯强度均先升高后下降,相对密度和抗弯强度在TiC含量5%时达到最高值,分别为94.61%和1327.20 MPa,显微硬度在TiC含量10%时达到最高值,为760 HV。随TiC含量增加,钢结硬质合金的断裂方式由韧性断裂向脆性断裂过渡。     

粉末冶金TC4-B4C原位反应制备TiC+TiB增强TC4基复合材料的显微组织和力学性能

以TC4和B₄C粉末为原料,通过放电等离子烧结法(SPS)并结合热挤压制备不同含量TiB和TiC增强TC4基复合材料,研究以TC4-B₄C为原位反应体系生成不同含量TiB和TiC对TMCs的微观组织和力学性能的影响规律及其高温力学性能。结果表明:原位生成的TiC和TiB与基体结合牢固,TiC呈类球形颗粒状,TiB呈晶须状;增强相在基体中呈现出沿一次颗粒边界分布的三维网络状形貌;与未增强TC4合金相比较,复合材料基体晶粒显著细化,并存在较高的位错密度,TC4基复合材料的室温和高温性能得到显著提升;在室温拉伸下,当B₄C的含量(质量分数)为0.5%时,基体的连通性较好,表现出较高的强度(抗拉强度1246 MPa)和较好的伸长率(12.4%);在400℃下进行拉伸时,当B₄C的含量为1.64%时,TC4基复合材料的抗拉强度和伸长率分别为1112 MPa和6.9%。     

TiC含量对W-30Cu/TiC复合材料显微组织和性能影响研究

经简化预处理后,采用化学法制得W–30Cu/(0-4) wt.% TiC复合粉末,在400MPa的压力下将制得的复合粉末压制成毛坯块体试样,随后在1300 °C下烧结1 h制得块体复合材料试样。采用场发射扫描电子显微镜来表征原始W 和TiC粉末、预处理后的W和TiC粉末、化学法制得的W–30Cu/(0, 0.25, 0.5, 1, 2, 3, 4) wt.% TiC复合粉末的显微形貌,以及制得的W–30Cu/TiC复合材料的显微结构。本文对不同TiC含量对W–30Cu/TiC复合材料的性能（如相对密度、硬度、导电性和抗弯强度等）进行研究。结果表明：对简单预处理后的W、TiC粉末化学镀Cu所获得的W–30Cu/TiC复合粉末的显微结构均匀。TiC含量低于1%时,W–30Cu/TiC复合材料的抗弯强度和硬度随TiC含量的增加而显著增大。而导电性则随TiC含量增加而减小,但仍高于国家标准值。添加一定量的TiC有利于获得综合性能能较好的W–30Cu/TiC复合材料。     

热循环对TiC／W复合材料组织和性能的影响

采用真空热压法制备TiC／W复合材料,研究了电子束热循环处理对其组织性能的影响。结果表明,电子束热循环处理对TiC／W复合材料试样表面造成了明显的损伤,试样局部表面熔化严重,冷却后呈波纹状。经热循环处理后TiC／W复合材料的微观结构发生了明显的变化：晶内位错密度增大,晶界处形成位错塞积群。此外,热循环处理导致TiC／W复合材料的抗弯强度下降,使试样表面以下200μm深度内显微硬度提高。     

不同(TiB+TiC)含量对颗粒增强钛基复合材料组织和性能的影响

利用海绵钛与B4C粉末之间的自蔓延高温合成反应,经普通熔铸工艺制备了TiB晶须和TiC粒子增强的钛基复合材料.研究了不同TiC、TiB含量对颗粒增强钛基复合材料组织和性能的影响.     

TiC颗粒增强钛基复合材料的制备及其微观组织

采用直接加入TiC粉的方法制备了原位自生TiC增强钛基复合材料，此法与国内研究者常用的加入石墨粉的方法相比，制备的复合材料成分准确，易于控制。制备的复合材料由Ti和TiC相组成，其中TiC为初生树枝状和短棒状共晶组成。TEM研究发现：还存在0．3-0．6μm的规则块状TiC，多分布在晶界上；TiC颗粒与基体界面干净、无反应层，基体中存在较多的位错，且位错线上存在析出物。     

Effect of B4C on the Microstructure and Mechanical Properties of As-Cast TiB＋TiC/TC4 Composites

Different additions of B4C were introduced into TC4 to alter the microstructure and mechanical properties.The morphologies of reinforcements are related to the solidification paths.The refinement of lamellar spacing k is based on the precipitation pattern of b-phases.Microhardness,compression elastic modulus(Ec),and elastic modulus of the matrix(Em)appear non-linear relationships with B4C additions.Due to the refinement of lamellar spacing with Hall–Petch-type relationships,and the solution strengthening of C on the a + b matrix,the effect of reinforcements on the mechanical properties will be more efficient when the additions of B4C are no more than 0.19 wt%.When the additions of B4C are more than 0.19 wt%,the efficiency will decrease.     

颗粒尺寸对微波烧结多孔NiTi合金的显微结构及力学性能的影响

以不同颗粒尺寸的Ni/Ti粉末为原料,采用微波烧结技术制备了多孔NiTi合金,并系统考察了颗粒尺寸对多孔NiTi合金的显微结构和力学性能的影响。结果表明,随着颗粒尺寸的减小,多孔NiTi合金中的Ti2Ni和Ni3Ti第二相减少而单质Ni相消失。同时,多孔NiTi合金的孔隙形貌由带尖角的不规则形状向近球形转变。此外,多孔NiTi合金的孔隙率和孔径随着颗粒尺寸的增大而增大,而洛氏硬度、抗压强度和抗弯强度均下降。因此,减小颗粒尺寸有利于获得理想的显微结构(纯净的物相和均匀的孔隙结构)和提高微波烧结多孔NiTi合金的力学性能。     

Characterization of (TiB + TiC)/TC4 in situ titanium matrix composites prepared by laser direct deposition

Preliminary characterization of microstructure and mechanical properties of (TiB + TiC)/TC4 in situ titanium matrix composites prepared by laser direct deposition is reported in this paper. The results indicate that in situ reaction occurred during laser direct deposition of coaxially fed mixed powders from TC4 and B₄C. Reinforcements of TiB and TiC with a fraction of about 25 vol.% were formed with feeding 5 wt.% B₄C. The morphology of TiB tended to be needle-like and prismatic, while TiC appeared as granular. Small amount of un-reacted B₄C with reduced size remained within the composites. A thin skull of reaction product formed around the un-reacted B₄C weakened its interface bonding with the titanium alloy matrix, resulting in less outstanding properties of the composites.     

Microstructure and wear properties of TiC/FeCrBSi surface composite coating prepared by laser cladding

Titanium carbide particles reinforced Fe-based surface composite coatings were fabricated by laser cladding using a 5 kW CO₂ laser. The microstructure, phase structure and wear properties were investigated by means of scanning electron microscopy, transmission electron microscopy and X-ray diffraction, as well as dry sliding wear test. The results showed that TiC carbides were formed via in situ reaction between ferrotitanium and graphite in the molten pool during the laser-clad process. The morphology of TiC is mainly cubic and dendritic form; and the TiC carbides were distributed uniformly in the composite coating. The TiC/matrix interface was found to be free from cracks and deleterious phases. The coatings reinforced by TiC particles revealed higher wear resistance and lower friction coefficient than that of the substrate and FeCrBSi laser-clad coating.     

高体积含量TiC/Fe复合材料的制备及力学性能

以TiC粉、还原铁粉和羰基铁粉为原料,采用行星球磨混料、冷压成型后无压烧结工艺制备了TiC颗粒体积含量为70%~90%的TiC/Fe复合材料,重点研究了羰基铁粉添加量、烧结温度及TiC体积含量对TiC/Fe复合材料的微观结构和力学性能的影响。结果表明:羰基铁粉的最佳添加量为铁基体粉体积含量的60%。当TiC体积含量一定时,随烧结温度的升高,TiC/Fe复合材料的相对密度、维氏硬度与弯曲强度均先增大后减小,经1500℃烧结后,复合材料的综合性能最佳。其中,70%TiC/Fe的相对密度及弯曲强度最高,分别为99.5%和437MPa;80%TiC/Fe的维氏硬度最大,为12.2GPa。     

Effect of particle size on the microstructure and thermal conductivity of Al/diamond composites prepared by spark plasma sintering

Spark plasma sintering (SPS) was used to fabricate Al/diamond composites. The influence of diamond particle size on the microstructure and thermal conductivity (TC) of composites was investigated by combining experimental results with model prediction. The results show that both composites with 40 μm particles and 70 μm particles exhibit high density and good TC, and the composite with 70 μm particles indicates an excellent TC of 325 W·m⁻¹·K⁻¹. Their TCs lay between the theoretical estimated bounds. In contrast, the composite with 100 μm particles demonstrates low density as well as poor TC due to its high porosity and weak interfacial bonding. Its TC is even considerably less than the lower bound of the predicted value. Using larger diamond particles can further enhance thermal conductive performance only based on the premise that highly dense composites of strong interfacial bonding can be obtained.     

Spark plasma sintering consolidation of nanostructured TiC prepared by mechanical alloying

Spark plasma sintering technique was used for the consolidation of nanostructured titanium carbide synthesized by mechanical alloying in order to avoid any important grain growth of the compact materials. The TiC phase was obtained after about 2 h of mechanical alloying. Towards the end of the milling process (20 h), the nanocrystalline powders reached a critical size value of less than 5 nm. Some physical and mechanical properties of the consolidated carbide were reported as a function of the starting grain size powders obtained after different mechanical alloying durations. The crystalline grain size of the bulk samples was found to be increased to a maximum of 120 nm and 91 nm for carbides mechanically alloyed for 2 h and 20 h respectively. The Vickers hardness showed to be improved to about 2700 Hv for a maximum density of 95.1% of the bulk material.     

Effect of carbon content on microstructure and property of TiC/Ti-6Al-4V composites

TiC reinforced Ti-6Al-4V matrix composites were fabricated by consumable arc-melting technology utilizing the reaction between titanium and graphite. The phase composition, microstructure and hardness of the TiC/Ti-6Al-4V composites were investigated by XRD, SEM and hardness testing equipment, respectively. The results show that the reinforcements are distributed uniformly in the matrix alloy. With the carbon content of the composites increasing from 0.15% to2.0%, the morphology of TiC transforms from particle into short-bar shape or chain-type consisting of featheriness or wheat-shape and finally into dendritic. Simultaneously, the hardness of the composites increases. The formation mechanisms of TiC can be analyzed as follows： the growth of dendritic primary TiC before the peritectic reaction is dominated by the solute concentration gradient, after peritectic reaction, the nucleation and growth of TiC in β-Ti leads to its forming of short-bar shape. The dendritic TiC mainly is distributed in the matrix grain, but the short-bar shape TiC mainly segregates at the grain boundary, especially at the triangular grain boundaries.