Effects of TiB2 particle size on the microstructure and mechanical properties of TiB2-based composites
Effects of TiB2 particle size on the microstructure and mechanical properties of TiB2-based composites
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DOI：
10.1016/j.ceramint.2018.08.270
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发表时间：
2019
影响因子：
5.2
通讯作者：
Ningjuan Wu;Fengdan Xue;Hailin Yang;Guoping Li;F. Luo;J. Ruan
中科院分区：
文献类型：
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作者：
Ningjuan Wu;Fengdan Xue;Hailin Yang;Guoping Li;F. Luo;J. Ruan
采用真空无压烧结方法，在1700 °C下保温1 h，制备了不同颗粒尺寸的TiB_2-25 %(Fe-Ni)和TiB_2-30 %(Fe-Ni)复合材料，详细研究了TiB_2颗粒尺寸对复合材料组织和性能的影响。采用X射线衍射仪、扫描电子显微镜、电子探针和透射电子显微镜对TiB_2基复合材料进行了物相分析和微观结构分析。实验结果表明，TiB_2基复合材料中只有TiB_2和γ(Fe，Ni)相，没有发现M2B、M23B6等脆性相。原始TiB_2颗粒形貌不规则，烧结后可观察到大量六方晶TiB_2颗粒。TiB_2的主要断裂模式受TiB_2颗粒尺寸的影响较大，随着TiB_2颗粒尺寸的增加，TiB_2基复合材料的主要断裂模式由穿晶断裂向沿晶断裂转变。TiB_2基复合材料的高韧性是裂纹偏转、裂纹分叉以及TiB_2颗粒与γ(Fe，Ni)粘结剂等综合增韧机制协同作用的结果。当TiB_2颗粒尺寸从1.97增至4.27 µm时，TiB_2基复合材料的相对密度、维氏硬度、抗弯强度、力学性能等TiB_2基复合材料的断裂韧性降低。TiB2颗粒尺寸为1.97 µm的TiB2-30 %(Fe-Ni)复合材料的相对密度达到98.20 ± 0.20%，维氏硬度达到14.00 ± 0.40 Gpa，抗弯强度达到1000 ± 30 ，断裂韧性达到19.26 ± 0.72 Mpa M1/2。
TiB2–25 vol% (Fe-Ni) and TiB2–30 vol% (Fe-Ni) composites with different TiB2particle size were fabricated by vacuum pressureless sintering at 1700 °C for 1 h. The influences of TiB2particle size on the microstructure and mechanical properties was studied in detail. The phase analyses and microstructure of TiB2-based composites were investigated by X-ray diffraction, SEM, EPMA, and TEM. The experimental results showed that only TiB2and γ(Fe, Ni) phases in the TiB2-based composites, not any other brittle phases such as M2B, M23B6can be found. The morphology of raw TiB2particles was irregular, however, many hexagonal crystals TiB2grains were observed after sintering. The change of dominant fracture mode was strongly affected by the grain size of TiB2particles, and the dominant fracture mode of TiB2-based composites transformed from trans-granular fracture to inter-granular fracture as the TiB2particle size increasing from 1.97 to 4.27 µm. The high-toughness of TiB2-based composites was due to the synergetic action of comprehensive toughening mechanisms, including crack deflection, crack branching, as well as the strong bonding strength between TiB2grains and γ(Fe, Ni) binder, etc. As TiB2particle size increasing from 1.97 to 4.27 µm, the relative density, Vickers hardness, flexural strength, and fracture toughness of the TiB2-based composites decreased. The relative density, Vickers hardness, flexural strength and fracture toughness of TiB2–30 vol% (Fe-Ni) composites with the TiB2particle size of 1.97 µm reached up to 98.20 ± 0.20%, 14.00 ± 0.40 GPa, 1000 ± 30 MPa, and 19.26 ± 0.72 MPa m1/2, respectively.