Effect Of Ni-Ti Alloy On The Microstructure And Mechanical Properties Of Ti(C,N)-based Cermets

As a new kind of tool materials, the Ti(C,N) -based cermets have been widely used in recent years due to many of their good properties. We prepared the samples that had different Ni-Ti alloy content by the traditional method of powder metallurgy and explained macro mechanical properties of this material by means of XRD, SEM, EDX and so on.The thesis is composed of five chapters. In the first chapter, the microstructure, properties of Ti(C,N)-based cermets as well as its development history were introduced. Meanwhile, the trend of Ni-Ti shape memory alloy was also briefed.In Chapter Two, experimental raw materials and preparation techniques of Ti (C,N)-based cermets were introduced simply.In Chapter Three, the testing method of mechanical properties and describing method of microstructure of Ti(C,N)-based cermets were focused on.In Chapter Four, the composition-microstructure-property relationship of Ti(C,N)-based cermets were discussed, and the effect of different Ni-Ti alloy addition on the microstructure and mechanical properties of Ti(C,N)-based cermets were reviewed. The conclusion of this study can be summarized as follows:(1)Within a certain range, the microstructure became finer with the increasing of Ni-Ti alloy addition, What' more, there was classical black core/grey rim structure in the microstructure.(2)Before the addition of Ni-Ti alloy, hard phase was nearly spherical shape; the shape of hard phase became multiangular with the increasing of Ni-Ti alloy, the interface between hard phase and binder phase presented line.(3) Fracture micrographs show that main failure mode of the Ti(C,N)-based cermets is amixed one, i.e., transgranular and intergranular fractures both exist.(4) While transverse rupture strength and fracture toughness of cermets had a great rise with the increasing of Ni-Ti alloy addition, but the change of hardness is not obvious; the cermets obtain the best comprehensive mechanical properties when the addition of Ni-Ti alloy is 15 wt %.Chapter five summarized the whole thesis and gave some advice on future works.