球磨时间对粉末冶金制备Ti35Nb2.5Sn/10HA生物复合材料微观组织的影响(英文)

采用高能机械球磨和脉冲电流活化烧结方法制备了一种新型的β-钛合金基体的Ti35Nb2.5Sn/10HA生物复合材料。研究了机械球磨不同时间的Ti35Nb2.5Sn10HA粉体以及烧结样品的微观组织。结果表明:经机械球磨8h后,粉体中的α-钛开始向β-钛转化。当球磨时间达到12h时,球磨粉体中的α-钛相完全转化为β-钛相,而且得到超细尺寸的复合粉体。用球磨12h的粉末烧结制备的复合材料具有超细晶粒结构,烧结得到的复合材料的硬度和相对密度都随着球磨时间的延长而增加。     

球磨与烧结对Al2Ti3V2ZrB/2024Al复合材料组织与硬度的影响

利用粉末冶金方法制备了Al2Ti3V2ZrB/2024Al复合材料,研究了球磨工艺和烧结温度对复合材料微观组织和硬度的影响。结果表明,球磨时过高的球磨速度或过长的球磨时间均会造成Al2Ti3V2ZrB颗粒的团聚,影响复合材料的组织均匀性。在球磨速度为150r/min下球磨5h,Al2Ti3V2ZrB颗粒在2024Al基体中的分布最均匀,复合材料的硬度最高。当烧结温度低于510℃时,Al2Ti3V2ZrB颗粒在2024Al基体中分布比较均匀,复合材料密度和硬度随烧结温度升高逐渐增加;超过510℃后Al2Ti3V2ZrB颗粒开始团聚,复合材料密度和硬度下降,在510℃制备的复合材料具有最高的硬度。     

机械合金化对W-20Cu复合材料的显微组织与性能的影响

采用机械合金化结合粉末冶金技术制备W-20Cu（vo1％）复合材料。利用扫描电镜和金相显微镜对不同球磨时间的W-20Cu复合材料显微组织进行表征，并对材料的各项物理性能进行测试。结果表明，随着球磨时间的延长，W-20Cu烧结体的组织越来越均匀，Cu相分布也越来越均匀。W-20Cu烧结体密度、收缩率、硬度、抗弯强度随球磨时间的延长而增大；球磨20h的W-20Cu复合粉烧结体热导率达到峰值（130．61Wm^-1K^-1），继续球磨，热导率减小。综合考虑所有研究结果，通过机械合金化所制备的W-Cu复合粉体可以获得具有优异综合物理性能的W-20Cu复合材料。     

机械球磨制备nHA-Ti复合粉末及其组织特征初探

以无水乙醇为球磨助剂，采用机械球磨方法制备了纳米羟基磷灰石．钛（nHA-Ti）复合粉末。利用X射线衍射（XRD）、扫描电子显微镜（SEM）和能谱分析仪（EDS），研究了球磨过程中（5-40h）复合粉末的相组成和微观组织；通过电子探针（EPMA）对Ca元素面扫描，分析了球磨过程中复合粉末的均匀化效果。结果表明，随着球磨时间的延长，复合粉末逐渐细化和均匀化，球磨30h可使复合粉末形成nHA弥散分布在Ti大颗粒上的包覆状粉末结构，且复合粉末中nHA获得了较好的均匀化效果。     

活化烧结制备W-Cu复合材料及其性能

研究添加元素Ni对W-Cu复合材料组织和性能的影响.利用预混粉、机械球磨和活化液相烧结法制备不同Ni含量W-Cu复合材料,采用电子扫描显微镜、X射线衍射仪、激光导热仪等对复合材料的显微组织、物相、热导率、热膨胀系数和硬度进行检测与分析.结果表明:当W-Cu复合材料中不添加Ni元素时,W颗粒团聚形成闭合孔隙,液相Cu无法...     

机械球磨Ti_(50)Al_(50)复合粉的压制特性

研究了机械球磨Ti50 Al50 复合粉的组织与压制特性。结果表明 ,球磨导致粉末硬度增加 ,压制特性变差 ,这是由于球磨使层片结构细化 ,Ti和Al组元晶体缺陷增加和晶粒细化造成的 ;但球磨 3h形成纳米晶复合粉后 ,尤其是在球磨 7.5h开始发生非晶转变后 ,进一步球磨 ,粉末压制特性变化并不明显     

不同TiN含量整体式PCBN复合材料微观组织及性能研究

在高温高压烧结条件下以TiN为主要结合剂,加入一定量的Al,研究TiN含量对整体聚晶立方氮化硼(PCBN)复合材料微观组织与力学性能的影响。分别对烧结样品进行物相组成分析、微观结构观测以及体积密度和硬度测试。结果表明:CBN与结合剂TiN、Al反应生成TiB₂、AlN,TiN与Al发生反应生成Al₃Ti ,TiN与反应生成物AlN、TiB₂、Al₃Ti等构成黏结相均匀分布于 CBN晶界周围,牢固地将CBN 晶粒黏结在一起,有效地提高了整体PCBN复合材料的结合强度。低含量TiN对整体PCBN的致密度和硬度均有一定程度的提升,在TiN、Al、CBN的质量分数分别为10%、10%、80%时,整体PCBN复合材料的力学性能达到最佳。      

轧制变形对网状结构TiB_w/Ti复合材料组织与力学性能的影响(英文)

通过反应热压技术成功制备出网状结构TiB晶须增强纯钛(TiBw/Ti)复合材料。原位合成的TiB晶须分布在大尺寸Ti基体颗粒周围形成网状结构。这种新型的网状结构TiBw/Ti复合材料表现出优异的综合力学性能。为了进一步改善力学性能及指导后续塑形变形加工,研究这种新型复合材料的轧制变形行为。结果表明:由于基体的形变强化,这种新型TiBw/Ti复合材料的强度可以通过轧制变形得到有效的提高,并且强度水平随着变形量的增加而增加。其中,通过轧制变形,可以使8.5%TiBw/Ti复合材料的强度从842MPa提高到 1030 MPa。需要指出的是,随着变形量的增加,TiB晶须的断裂程度也增加,这一点对复合材料的力学性能是不利的。     

Tribological behavior of self lubricating Cu/MoS2 composites fabricated by powder metallurgy

The effects of MoS₂ content on microstructure, density, hardness and wear resistance of pure copper were studied. Copper-based composites containing 0–10% (mass fraction) MoS₂ particles were fabricated by mechanical milling and hot pressing from pure copper and MoS₂ powders. Wear resistance was evaluated in dry sliding condition using a pin on disk configuration at a constant sliding speed of 0.2 m/s. Hardness measurements showed a critical MoS₂ content of 2.5% at which a hardness peak was attained. Regardless of the applied normal load, the lowest coefficient of friction and wear loss were attained for Cu/2.5MoS₂ composite. While coefficient of friction decreased when the applied normal load was raised from 1 to 4 N at any reinforcement content, the wear volume increased with increasing normal load. SEM micrographs from the worn surfaces and debris revealed that the wear mechanism was changed from mainly adhesion in pure copper to a combination of abrasion and delamination in Cu/MoS₂ composites.     

Nb-Cr掺杂原位合成Al2O3/TiAl复合材料的组织与性能

采用原位热压工艺,在Ti-Al-TiO2-Nb2O5体系中加入Cr2O3原位合成Al2O3/TiAl复合材料.借助X射线衍射分析、SEM分析及力学性能分析,研究了Nb-Cr掺杂复合强化Al2O3/TiAl复合材料的反应过程、微观结构及力学性能.结果表明Nb-Cr掺杂原位合成Al2O3/TiAl复合材料能够细化晶粒并通过微合金化增强增韧TiAl复合材料.     

TiC颗粒强化Ti-30Fe复合材料的摩擦行为

将Ti、Fe和TiC粉末进行低温球磨,并结合放电等离子烧结制备Ti-Fe-xTiC(x=0,3,6,9,质量分数％)复合材料.结果表明:该复合材料中含有β-Ti、β-Ti-Fe、η-Ti4Fe2O0.4以及TiC颗粒.显微组织随着TiC添加量的增加而显著细化.粘着磨损是Ti-Fe-xTiC复合材料的主要磨损机制.随着T...     

自生TiC颗粒增强高锰钢基复合材料的研制

用铸造法成功制备了自生TiC颗粒增强的高锰钢基复合材料,研究了其显微组织和力学性能与Ti含量的关系.结果表明,高锰钢基复合材料的显微组织由TiC颗粒,奥氏体和合金渗碳体组成.其中合金渗碳体随着Ti含量的升高而逐渐粗大,且连续分布于晶界处.随着Ti含量的升高,高锰钢基复合材料中TiC颗粒的数量增多,硬度逐渐升高.含5%Ti的复合材料热处理态硬度达到HRC39,是纯高锰钢的2.6倍.随着Ti含量的升高,高锰钢基复合材料的冲击韧度大幅降低.其中,含5%Ti的复合材料经水韧处理后冲击韧度达到60J/cm2.     

Influence of the processing route on the properties of Ti(C,N)-Fe15Ni cermets

This study aims to understand the influence of powder preparation and processing steps on the microstructure and properties of Ti(C,N)-Fe15Ni cermets with 70 and 80 vol% of ceramic phase. Two routes were used for powder preparation: (i) a colloidal approach, consisting of the preparation of stable aqueous suspensions of the powder particles and spray-drying to obtain easy-to-press granules, and (ii) conventional powder metallurgy route, consisting on wet ball milling of powders, with subsequent drying in rotary evaporator. The resultant powder mixtures were uniaxially pressed and sintered in high-vacuum at 1450 °C for 2 h. Sintered samples were characterized in terms of their density, porosity, microstructure (FESEM, image analysis), composition (EDX and XRD), small-scale hardness and sliding contact response by means of massive nanoindentation and nanoscratch testing. C content of the mixture powders was lower for conventional route, lost during milling. After sintering, all the materials, despite the processing route and composition, show C reduction, although that outflow is higher for the conventional powder metallurgy route, and more evident for the composition with higher binder content. As a result, COL samples exhibit a more homogeneous microstructural assemblage, higher small-scale hardness and mechanical integrity under sliding contact conditions. Compositions of materials must then be adjusted to adequate initial C addition with respect to the employed processing route, to account for the effects of the mixtures preparation stage.     

Prediction of effect of volume fraction, compact pressure and milling time on properties of Al-Al2O3 MMCs using neural networks

An artificial neural network (ANN) model was developed to predict the effect of volume fraction, compact pressure and milling time on green density, sintered density and hardness of Al-Al₂O₃ metal matrix composites (MMCs). Al-Al₂O₃ powder mixtures with various reinforcement volume fractions of 5, 10, 15% Al₂O₃ and milling times (0 h to 7 h) were prepared by mechanical milling process and composite powders were compacted at various pressure (300, 500 and 700 MPa). The three input parameters in the proposed ANN were the volume fraction, compact pressure and duration of the milling process. Green density, sintered density and hardness of the composites were the outputs obtained from the proposed ANN. As a result of this study the ANN was found to be successful for predicting the green density, sintered density and hardness of Al-Al₂O₃ MMCs. The mean absolute percentage error for the predicted values didn’t exceed 5.53%. This model can be used for predicting Al-Al₂O₃ MMCs properties produced with different reinforcement volume fractions, compact pressures and milling times.     

Effects of rolling deformation on microstructure and mechanical properties of network structured TiBw/Ti composites

TiB whiskers reinforced pure Ti (TiB_w/Ti) composites with a novel network microstructure were successfully fabricated by reaction hot pressing (RHP). TiB whiskers are in situ synthesized around the large pure Ti matrix particles, and subsequently formed into TiB_w network structure. The novel TiB_w/Ti composites with a network microstructure exhibit a superior combination of mechanical properties. In order to further improve the mechanical properties and guide the subsequent plastic forming, the rolling deformation behavior of the novel composites was investigated. The results show that the strength of the novel TiB_w/Ti composites can be effectively enhanced by rolling deformation due to the matrix deformation strengthening effect, and increased with increasing the rolling reduction. The strength of 8.5%TiB_w/Ti (volume fraction) composite is significantly increased from 842 MPa to 1030 MPa by rolling deformation. It is certain that the TiB whiskers are gradually broken with increasing the rolling reduction, which is harmful to the mechanical properties of the composites.     

放电等离子烧结TiB/Ti-1.5Fe-2.25Mo复合材料的微观组织与力学性能

采用放电等离子烧结技术原位合成了TiB增强Ti?1.5Fe?2.25Mo复合材料,研究了烧结温度对复合材料微观组织和力学性能的影响规律。结果表明,随着烧结温度的升高,钛合金中 TiB 晶须的长细比迅速减小;然而,复合材料的相对密度及TiB的体积含量随着烧结温度的升高而不断增大。由于TiB晶须长细比的减小会导致复合材料强度的降低,而复合材料的相对密度及TiB体积含量的增大又会带来复合材料强度的增加,因此,在这两种因素的共同作用下,最终导致 TiB/Ti?1.5Fe?2.25Mo复合材料的弯曲强度随着烧结温度的升高而缓慢增大。在烧结温度为1150°C 时,TiB/Ti?1.5Fe?2.25Mo复合材料具有最大的弯曲强度1596 MPa。     

Microstructures and mechanical properties of Al 2519 matrix composites reinforced with Ti-coated SiC particles

Ti-coated SiC_p particles were developed by vacuum evaporation with Ti to improve the interfacial bonding of SiC_p/Al composites. Ti-coated SiC particles and uncoated SiC particles reinforced Al 2519 matrix composites were prepared by hot pressing, hot extrusion and heat treatment. The influence of Ti coating on microstructure and mechanical properties of the composites was analyzed by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The results show that the densely deposited Ti coating reacts with SiC particles to form TiC and Ti₅Si₃ phases at the interface. Ti-coated SiC particle reinforced composite exhibits uniformity and compactness compared to the composite reinforced with uncoated SiC particles. The microstructure, relative density and mechanical properties of the composite are significantly improved. When the volume fraction is 15%, the hardness, fracture strain and tensile strength of the SiC_p reinforced Al 2519 composite after Ti plating are optimized, which are HB 138.5, 4.02% and 455 MPa, respectively.     

Prediction of Compressive Strength of Biodegradable Mg–Zn/HA Composite via Response Surface Methodology and Its Biodegradation

This work aimed to fabricate magnesium zinc/hydroxyapatite(Mg–Zn/HA) composite via powder metallurgy method and to develop a mathematical model to predict the compressive strength of the composite using response surface methodology method. The effect of various mechanical milling parameters, milling speed(200–300 r/min), ball-to-powder weight ratio(5–12.5)and HA content(2.6–10 wt%) on the compressive strength of Mg–Zn/HA composite was investigated. The model shows that high compressive strength of Mg–Zn/HA composite was achieved when the powders were prepared with high milling speed and ball-topowder weight ratio and low HA content. The mathematical model was adequate with error percentage lower than 3.4%. The microstructure of Mg–Zn/HA composite with different process parameters revealed that fine microstructure was observed at high milling speed and ball-to-powder weight ratio while agglomeration of HA was found in composite with 10 wt% HA. The agglomeration of HA led to degradation of interfacial bonding strength between matrix and reinforcement phases and hence decreased the overall compressive strength of Mg–Zn/HA composite. Biodegradation test revealed that sample with higher HA content had more weight gain and there was more formation of hydroxyapatite. Mg–Zn/HA composite with 8 wt% HA was found to be the best candidate for implant application because it had considerable compressive strength and good biodegradation properties.     

热压烧结制备Al2O3/TiCN-Ni-Ti陶瓷复合材料的组织与性能

采用真空热压烧结方法制备Al2O3/Ti(C,N)-Ni-Ti陶瓷基复合材料,采用X射线衍射与扫描电镜分析材料的物相组成和显微结构,研究烧结工艺对材料物相组成、显微结构和力学性能的影响。结果表明:Ni和Ti的添加显著提高复合材料的强度和韧性;温度小于1 600℃时,复合材料的力学性能随热压温度的升高而升高;温度高于1 600℃时,温度升高及保温时间延长不仅会导致Al2O3晶粒的异常长大和Ti(C,N)的分解,而且会使Ni发生聚集现象,复合材料的力学性能下降;当烧结温度为1 600℃、保温时间为30 min时,制备的Al2O3/Ti(C,N)-Ni-Ti陶瓷复合材料的力学性能最佳,其相对密度达到99.4%,抗弯强度为820 MPa,断裂韧性达到9.3 MPa.m1/2。     

Effect of hydroxyapatite content on the microstructure,thermal and mechanical properties of Ti-based glassy alloy/hydroxyapatite composite prepared by spark plasma sintering

In the present paper, the effects of hydroxyapatite (HA) content on the microstructure, thermal and mechanical properties of Ti-based glassy alloy/HA composite prepared by spark plasma sintering (SPS) are investigated. The microstructure of the composites is homogeneous when the HA is lower than 2 wt%. When the HA content is higher than 3 wt%, the crystalline precipitates with size of less than 5 nm are distributed in the glassy matrix. HA decomposes during sintering procedure for the composite with high HA content. With increasing HA addition, compressive strength decreases. Especially for the HA content is over 2 wt%, the strength decreases sharply because of partial crystallization of glassy alloy matrix.