( 1. 华中科技大学 塑性成形模拟及模具技术国家重点实验室,
武汉 430074;
2. 三峡大学 机械与材料学院, 宜昌 443002;
3. 南京航空航天大学 材料科学与技术学院, 南京 210016)
摘 要: 采用真空烧结工艺制备Ti(C, N)基金属陶瓷, 测定了材料的力学性能。 结果表明, 其力学性能与未加纳米粉的金属陶瓷相比, 硬度略有升高, 但横向断裂韧性提高了近一倍。 断口形貌和微观组织分析表明: 金属陶瓷的断口形貌与其强韧性有着密切的关系。 纳米粉的加入降低了原始粉末的平均粒度, 使得金属陶瓷硬质相的粒度降低, 减小了晶粒间的平均自由程。 镶嵌于大颗粒环形相和弥散分布于粘结相中的细小硬质相颗粒, 对裂纹的形成和扩展起到阻碍作用, 会使金属陶瓷因裂纹扩展途径发生偏转而增韧。
关键字: Ti(C, N)基金属陶瓷; 断口形貌; 增韧机理; 力学性能
( 1. State Key Laboratory of Plastic Forming Simulation and Die and Mould Technology, Huazhong University of Science and Technology,
Wuhan 430074, China;
2. College of Mechanical and Materials Engineering,
China Three Gorges University, Yichang 443002, China;
3. College of Materials Science and Technology,
Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China)
Abstract: The Ti(C, N)-based cermets were produced by vacuum sintering technology, and the mechanical properties were measured. The results show that the hardness of nano-composite Ti(C, N)-based cermets slightly increases, while the transverse rupture strength (TRS) increases by a factor of two times compared with micron cermets. The analysis of appearance of fracture and microstructure indicates that there is compact relation between appearance of fracture and toughness. With the addition of nano-structured powders, the mean particle size of raw powders decreases, the microstructure becomes finer and distributes evenly, and the average distance between grains reduces. Some small grains are found to be embedded in binder and the rim phases of big grains obstruct the form and extend of crack. The experiment results indicate that the toughening mechanisms of nano-composite cermets is crack deflection toughening.
Key words: Ti(C, N)-based cermets; appearance of fracture; toughening mechanisms; properties