(Ti,Nb)C_(x)复合材料的制备与性能表征

Preparation and performance characterization of(Ti,Nb)C_(x)composite material

以TiC与过渡族金属Nb为原料,在机械合金化(mechanical alloying,MA)下制备多种非化学计量比的(Ti,Nb)C_(x)聚晶金刚石(polycrystalline diamond,PCD)刀具结合剂。通过X射线衍射仪对复合材料烧结体的物相组成等进行分析,再通过扫描电子显微镜对复合材料的断口形貌进行观察,并用维氏硬度计测量复合材料的硬度和断裂韧性。结果表明:在1300~1700℃的范围内,温度越高TiC和Nb的固溶程度越好;在同一烧结温度下,(Ti,Nb)C_(x)复合材料的硬度随着金属Nb占比变大而逐渐升高;在同一金属Nb占比下,温度越高Nb与TiC的固溶程度越好。同时,(Ti,Nb)C0.5复合材料的力学性能最优,在1600℃时达到硬度最大值23.0 GPa,且其断裂韧性最高为7.20 MPa·m^(1/2)。

Objectives:The aim was to prepare a variety of non-stoichiometric(Ti,Nb)C_(x)PCD tool binder composites using TiC and transition metal Nb by mechanical alloying(MA)technology.The effects of different sintering temperatures and Nb contents on the phase compositions,microstructures,and mechanical properties of the composites were investigated to provide a scientific basis for optimizing the properties of PCD tool binders.The specific tasks included preparing(Ti,Nb)C_(x)composites with varying ratios,analyzing their solid-solution behavior at different temperatures,and evaluating their hardness and fracture toughness.Methods:High purity TiC and Nb powders were selected as raw materials for the experiment,and the MA technology was used to achieve uniform mixing of the two materials.In order to investigate the effect of sintering temperature on the properties of composite materials,various sintering temperatures ranging from 1300 to 1700℃were set.The sintered samples were subjected to phase analysis using an X-ray diffractometer,and the data were analyzed using Jade software.Subsequently,the fracture morphology of the sintered body was observed using scanning electron microscopy(SEM),and the hardness and fracture toughness of the composite materials were measured using a Vickers hardness tester.Results:Within the sintering temperature range of 1300 to 1700℃,the solid-solution degree of TiC and Nb gradually increases with the increase in temperature.At higher temperatures,the diffusion between TiC and Nb accelerates,forming a more stable solid-solution,and the phase composition tends to stabilize.At the same sintering temperature,the hardness of the(Ti,Nb)C_(x)composite increases gradually with the increase in Nb content,indicating that the introduction of Nb enhances the overall hardness of the composite.Especially when the sintering temperature is 1600℃,the(Ti,Nb)C0.50.5 composite exhibits the best mechanical properties with a hardness of 23.0 GPa and fracture toughness of 7.20 MPa·m1/2.The results show that under these temperature and ratio conditions,the composite achieves the best solid-solution state,has fewer internal defects,moderate grain size,and optimal mechanical properties.Conclusions:The sintering temperature and Nb content have significant impacts on the phase composition and mechanical properties of(Ti,Nb)C_(x)composite materials.Controlling these two parameters can optimize the hardness and toughness of the composite materials,thereby enhancing their application potential in PCD cutting tools.The higher sintering temperature is conducive to the full solid-solution of TiC and Nb,forming a more stable crystalline phase structure and improving the mechanical properties of the material.Future research could explore the influences of introducing other transition group metals on the properties of composite materials in order to develop higher-performance PCD tool binders.Others:Although the main objective of this study is to optimize the performance of(Ti,Nb)Cx PCD tool binders,the mechanical alloying techniques and analytical methods used in this research have the potential for broader applications.The mechanical alloying technology is not only suitable for the development of PCD tool materials but also for the preparation of other high-performance composite materials.At the same time,the combination of X-ray diffraction analysis and scanning electron microscopy provides valuable data support for the field of materials science,which helps deepen the understanding of the microstructure and phase composition of materials,thereby promoting research progress in the field.