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1.
In situ Ti/TiB composites (Ti-6Al-4V matrix reinforced with TiB phase) with different volume fractions of the TiB phase, have been produced by consolidation of rapidly solidified Ti-6Al-4V alloys with different levels of boron addition. The microstructural examination of such composites shows that the reinforcing phase has a fine grain size and a uniform distribution throughout the matrix. The Young's moduli of the in situ composites have been determined experimentally to study the strengthening effect of the TiB phase. It was found that the Young's modulus of an in situ composite with 10 vol % TiB phase can be increased to 140 GPa, compared to 116.7 GPa for the matrix alloy. The theoretical predictions are in good agreement with the present experimental results and other results of similar composites obtained by the reactive sintering technique.  相似文献   

2.
1. IntroductionTitanium diboride ceramic has some special proper-ties, such as high melting points, high hardness, highelectrical and thermal conductivity. These special prop-erties make it has a great potential to be used as contactmaterials. However, this application is still limited forpoor sinterability and brittle of TiB2[1~3]. To improve itssinterability and toughness, some metals were selected asadditives for liquid phase sintering of TiB2. Metals likeFe, Co and Ni were studied in m…  相似文献   

3.
采用挤压铸造法制备不同体积分数的TiB2P/Al复合材料, 利用扫描电镜、 硬度计、 拉伸试验机等对复合材料的室温力学性能进行了研究, 系统地分析了体积分数和热处理工艺对材料力学性能的影响。结果表明: 挤压铸造TiB2P/Al复合材料的布氏硬度、 抗弯强度和弹性模量随增强相TiB2体积分数的增加而提高。45% TiB2P/Al复合材料T6处理后硬度和抗弯强度分别比退火态时提高了23%和40%, 但热处理状态对弹性模量的影响不大。  相似文献   

4.
利用激光熔化沉积工艺制备了TiB+TiC增强相体积分数分别为9%、11%、22%及57%的4种(TiB+TiC)/TA15原位钛基复合材料。随增强相含量提高,TiB形态由片层状向棱柱状转化,TiC形态由不规则颗粒状向枝晶状转化,钛基复合材料硬度及弹性模量均显著提高而塑性明显下降。增强相体积分数约为9%的复合材料表现出较好的综合力学性能,增强相体积分数大于11%后复合材料的抗拉强度急剧降低。与激光熔化沉积态TA15钛合金相比,TiB+TiC增强相体积分数约为9%的复合材料抗拉强度(1040 MPa)及屈服强度(935 MPa)均提高约12%。  相似文献   

5.
The(TiB/Ti)-TiAl composites with a laminated structure composing of alternating TiB/Ti composite layers,α2-Ti3Al interfacial reaction layers of andγ-TiAl layers were successfully pre pared by spark plasma sintering of alternately stacked Tib2/Ti powder layers and TiAl powder layers.And the influence of thickness ratio of Tib2/Ti powder layers to TiAl powder layers on microstructure evolution and mechanical properties of the re sulting(TiB/Ti)-TiAl laminated composites were investigated systemically.The results showed that the thickening ofα2-Ti3Al layers which originated from the reaction of Ti and TiAl was significantly hindered by introducing Tib2particles into starting Ti powders.As the thickness ratio of Tib2/Ti powder layers to TiAl powder layers increased,the bending fracture strength and fracture toughness at room temperature of the final(TiB/Ti)-TiAl laminated composites were remarkably improved,especially for the(TiB/Ti)-TiAl composites prepared by Tib2/Ti powder layers with thickness of 800μm and TiAl powder layers with thickness of 400μm,whose fracture toughness and bending strength were up to 51.2 MPa·m1/2and 1456 MPa,respectively,293%and 108%higher than that of the monolithic TiAl alloys in the present work.This was attributed to the addition of high-performance network TiB/Ti composite layers.Moreover,it was noteworthy that the ultimate tensile strength at 700℃of(TiB/Ti)-TiAl composites fabricated by 400μm thick Tib2/Ti powder layers and 400μm thick TiAl powder layers was as high as that at 550℃of network TiB/Ti composites.This means the service temperature of(TiB/Ti)-TiAl laminated composites was likely raised by 150℃,meanwhile a good combination of high strength and high toughness at ambient tempe rature could be maintained.Finally,the fracture mechanism of(TiB/Ti)-TiAl laminated composites was proposed.  相似文献   

6.
原位合成TiC和TiB增强钛基复合材料   总被引:4,自引:0,他引:4  
分析了增强体TiC和TiB在钛中的原位生成机理,利用普通的熔铸设备,原位合成制备了TiC和TiB颗粒增强的钛基复合材料,SEM和X射线衍射的研究结果表明,TiC和TiB以不同形状在钛基体中生长,较为细小,且分布均匀,钛基复合材料的室温和高温性能了较大的提高。  相似文献   

7.
The in situ synthesized TiB reinforced titanium matrix composites have been prepared by spark plasma sintering at 800–1200 °C under 20 MPa for 5 min. The effects of sintering temperature and reinforcement volume fraction on flexural strength, Young’s modulus and fracture toughness of the composites are investigated. The titanium matrix consists of -Ti and β-Ti phases, and the volume fraction of β-Ti increases with increasing sintering temperatures. The in situ synthesized TiB reinforcements are distributed randomly and uniformly in matrix. The transverse section of TiB has a hexagonal shape aligned along [0 1 0] direction, and the crystallographic planes of the TiB needles are always of the type . The 10 vol% TiB reinforced composite sintered at 1000 °C exhibits excellent mechanical properties. The flexural strength, Young’s modulus and fracture toughness of this composite are 1560 MPa, 137 GPa and 8.64 MPa · m1/2, respectively.  相似文献   

8.
In situ TiB whisker reinforced Ti6Al4V (TiBw/Ti64) composites with a network architecture were extruded and heat treated in order to further improve their mechanical properties. The microstructure results show that the equiaxed network architecture was extruded to column network architecture and TiB whisker to alignment distribution. The transformed β phase is formed and the residual stress generated during extrusion obviously decreases after water quenching and aging processes. The tensile test results show that the strength, elastic modulus and ductility of the composites can be significantly improved by the subsequent extrusion, and then, the strength can be further improved by water quenching and aging processes after hot extrusion deformation. The elastic modulus of the as-sintered composites with a novel network microstructure follows the upper bound of Hashin-Shtrikman (H-S) theory before extrusion, while that of the as-extruded composites with a column network microstructure agrees well with the prediction from Halpin-Tsai equation.  相似文献   

9.
用粉末冶金原位合成法制备了TiB晶须增强钛基复台材料。利用扫描电镜和X射线衍射方法对经挤压变形后复合材料的微观结构进行了分析。在复合材料中观察到反应生成的TiB晶须。复合材料经过热挤压变形后,TiB晶须沿挤压方向定向排列。对挤压态TiBw/Ti复合材料进行高温压缩变形,TiB晶须在热压缩变形过程中发生转动或折断现象,变形温度越低,晶须折断现象越严重。  相似文献   

10.
将Ti合金插层引入(Ti+B_4C)反应原料和Ti合金底板之间,研究Ti合金插层厚度变化对超重力反应连接TiB2基陶瓷/Ti-6Al-4V梯度复合材料界面显微组织与力学性能的影响。热力学计算表明:合成反应的绝热温度远超Ti合金的熔点,可以保证不同厚度的Ti合金插层全部熔化。XRD、FESEM及EDS分析结果表明:在陶瓷和Ti合金底板之间形成梯度界面区,且随着Ti合金插层厚度的增加,梯度界面区的厚度也不断增大。自陶瓷基体至Ti合金底板,TiB_2和TiC_(1-x)的体积分数不断减少,而TiB的体积分数先增加而后减少,最终形成以TiB_2、TiC_(1-x)及TiB陶瓷相尺寸和分布为特征的梯度复合结构。而梯度连接区的硬度分布趋势更加平缓,其剪切强度不断提升。  相似文献   

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