Microstructure and mechanical properties of TiC particle enhanced high chromium iron
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摘要: 采用粉末冶金法（powder metallurgy，PM）和超固相线液相烧结技术（super solid phase line liquid phase sintering，SLPS）制备出TiC颗粒增强（TiCP）+含质量分数20%Cr的烧结高铬铸铁（high chromium cast iron，HCCI）复合材料。利用光学显微镜、扫描电子显微镜（scanning electron microscope，SEM）和X射线衍射仪（X-ray diffraction，XRD）研究了TiC颗粒增强相含量（质量分数）对TiCP/HCCI复合材料物相组成、显微组织和力学性能的影响，并开展了后续热处理研究。结果表明：超固相线液相烧结技术制备出的TiCP/HCCI复合材料相对密度均达97%以上，其物相组成为马氏体、奥氏体、M7C3碳化物和TiC。TiC颗粒主要沿着高铬铸铁中金属基体/碳化物界面分布，随着TiC含量增加，复合材料的硬度显著增加，达到HRC 67.2，但冲击韧性却逐步降低，合金断裂机制也由准解理性断裂向沿晶完全解理性断裂转变。经淬火处理后，该类TiCP/HCCI复合材料的硬度可进一步提升至HRC 69.3，有望成为硬度介于高铬铸铁和硬质合金之间的优秀耐磨材料。Abstract: TiC particle (TiCP) reinforced-sintered high chromium cast iron (HCCI) composites containing 20% Cr by mass were prepared by powder metallurgy (PM) and super solid phase line liquid phase sintering (SLPS). The effect of TiC particle content (mass fraction) on the phase composition, microstructure, and mechanical properties of the TiCP/HCCI composites was systematically studied by means of optical microscope, scanning electron microscope (SEM), and X-ray diffraction (XRD). The subsequent heat treatment research was also carried out. The results show that, the relative density of the TiCP/HCCI composites prepared by SLPS is above 97%, and the phase composition is composed of martensite, austenite, M7C3 carbide, and TiC. The TiC particles mainly distribute along the interface between the metal matrix and carbide in HCCI. With the increase of TiC content, the hardness of the composites increases to HRC 67.2, while the impact toughness decreases gradually. The fracture mechanism of the composites changes from the quasi cleavage fracture to the inter-granular cleavage fracture. After the quenched treatment, the hardness of the TiCP/HCCI composites can be further increased to HRC 69.3, which are expected to be the excellent wear-resistant materials with the hardness between HCCI and cemented carbide.
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Key words:
- TiC particles /
- high chromium cast iron /
- powder metallurgy /
- microstructure /
- mechanical properties /
- composites
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图 1 TiC（a）和HCCI（b）原料粉末颗粒显微形貌
Figure 1. SEM images of TiC (a) and HCCI (b) raw powder particles
图 2 TiC颗粒增强烧结高铬铸铁的实际密度、相对密度（a）和硬度（b）
Figure 2. Density, relative density (a), and hardness (b) of the TiC particle enhanced sintered HCCI
图 3 添加不同质量分数TiC增强颗粒的烧结高铬铸铁显微组织：（a）；0（b）5%；（c）10%；（d）15%；（e）20%
Figure 3. Microstructure of the TiC particle enhanced sintered HCCI with different TiC particle mass fraction: (a) 0; (b) 5%; (c) 10%; (d) 15%; (e) 20%
图 4 TiC 颗粒强化烧结态高铬铸铁X射线衍射图
Figure 4. X-ray diffraction patterns of the TiC particle enhanced sintered HCCI
图 5 TiC质量分数对烧结高铬铸铁抗弯强度和冲击韧性的影响
Figure 5. Effect of TiC particle mass fraction on the bending strength and toughness of the sintered HCCI
图 7 添加质量分数为15%TiC颗粒的HCCI显微形貌：（a）烧结态；（b）淬火态
Figure 7. SEM images of the TiCP/HCCI with 15% TiC particles by mass: (a) the sintered HCCI; (b) the quenched HCCI
图 8 淬火态TiCP/HCCI的X射线衍射图
Figure 8. X-ray diffraction patterns of the quenched TiCP/HCCI
图 9 淬火处理对烧结高铬铸铁力学性能的影响
Figure 9. Effect of the quenched treatment on the mechanical properties of the sintered HCCI
表 1 烧结高铬铸铁主要化学成分（质量分数）
Table 1. Chemical composition of the sintered high chromium cast iron
% C Cr Mo Si Ni Fe 2.50 19.28 1.58 0.68 0.96 余量 
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表 2 TiC增强颗粒粉末特性参数
Table 2. Characteristic parameters of the TiC reinforced powders
成分 特性参数 TiC粉 疏松海绵状，氧含量（质量分数）0.13%，游离
碳含量（质量分数）<0.26%，D50=430 nm
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表 3 淬火前后TiC颗粒强化烧结高铬铸铁硬度和力学性能
Table 3. Hardness and mechanical properties of the TiC particles enhanced sintered HCCI before and after the quenched treatment
TiC质量分数/
%处理状态 硬度，
HRC冲击韧性/
(J·cm−2)抗弯强度/
MPa0 烧结态 56.7 9.6 2017.8 淬火态 60.2 5.6 1577.1 5 烧结态 61.4 2.8 1334.2 淬火态 65.2 1.6 1149.8 10 烧结态 63.3 2.2 1077.5 淬火态 67.0 1.4 1095.0 15 烧结态 64.0 1.8 1053.2 淬火态 66.6 1.4 1089.7 20 烧结态 67.2 1.5 1049.0 淬火态 69.3 1.4 1028.8
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