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低成本TiH2粉末制备Ti/(TiB+TiC)复合材料的组织与性能

Microstructure and properties of Ti/(TiB+TiC) composites prepared by low-cost TiH2 powders

  • 摘要: 使用低成本的TiH2粉末代替纯钛粉,通过添加B4C原位生成TiB和TiC两种增强相,经过真空无压烧结及热挤压工艺制备出具有优异力学性能的Ti/(TiB+TiC)钛基复合材料,分析了制备工艺和增强相对复合材料组织与性能的影响。结果表明,TiH2粉末具有较好的烧结活性,脱氢烧结样品的相对密度可达97.7%;经热挤压工艺,相对密度进一步提升到99.9%,接近于全致密。增强相TiB为短纤维状,TiC为颗粒状,均匀分布在等轴α-Ti基体中,能抑制等轴晶的长大,细化晶粒。热挤压工艺能进一步细化晶粒,使组织更加均匀致密,挤压态钛基复合材料具有高硬度和良好的强塑性匹配。TiH2+4%B4C(体积分数)挤压态复合材料维氏硬度Hv0.3 310,屈服强度683 MPa,抗拉强度851 MPa,断后伸长率15.1%。

     

    Abstract: Ti/(TiB+TiC) titanium matrix composites with the excellent mechanical properties were prepared by vacuum pressureless sintering and hot extrusion by using low-cost TiH2 powders instead of pure titanium powders and adding B4C to in-situ produce TiB and TiC reinforcements. The effects of preparation technology and reinforcements on the microstructure and properties of the Ti/(TiB+TiC) composites were analyzed. The results show that the TiH2 powders have the good sintering activity, and the relative density of the sample after dehydrogenation and sintering can reach 97.7%, which is further increased to 99.9% after the hot extrusion as closed to full density. The TiB reinforcements are short fibrous, and the TiC reinforcements are granular, which are uniformly distributed in the equiaxed α-Ti matrix, restraining the growth of equiaxed grains and refining the grains. The hot extrusion process can further refine the grains and make the microstructure more uniform and compact, the as-extruded titanium matrix composites show the high hardness and good matching of strength and ductility. The TiH2+4%B4C (volume fraction) extruded composites have the Vickers hardness of Hv0.3 310, yield strength of 683 MPa, tensile strength of 851 MPa, and elongation of 15.1% after fracture.

     

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