激光熔覆TiC_p／Ni合金复合涂层中TiC颗粒的溶解析出行为与分布特征

在４５钢表面激光熔覆３０％ＴＩＣｐ／Ｎｉ基合金复合耐磨涂层，其组织由ＴｉＣ颗粒、γ－Ｎｉ固溶体枝状初晶及其晶间的Ｍ２３Ｃ６＋γ－Ｎｉ共晶组成。ＴｉＣ颗粒既分布在γ晶内，也可被固液界面推移至晶间与共晶共存。ＴｉＣｐ的形貌特征与其在激光熔覆过程中的溶解析出行为密切相关，其生长机制包括原位析出、桥接生长、独立形核生长和沉淀析出。

Dissolution and Precipitation of TiC Particles and Their Distribution in a Laser Clad 30vol.-% TiC_p/Ni-alloy Composite Coating

A 30vol.-% TiCp/Ni-alloy composite material was cladded on steel 1045 using a 2 kW laser.The clad layer of the coating presents TiC particles,primary γ-Ni dendrites and the eutectics of γ-Ni+ Cr,Fe)23C6 in the interdendritic regions.Depending mainly on their sizes,TiC particles can not only be trapped by the advancing solid/liquid interface and thus distribute within the γ-Ni dendrites,but also be pushed away by the interface into the interdendritic regions together with the eutectics. The morphology of TiC particles are closely related to their dissolution and precipitation behavior during laser claddin. The growing mechanism of TiC particles are as follows: (1) radiated or stapped lateral growth at the edges of original particles; (2) bridging growth of the particles in cluster; (3) faceted growth of newly independently nucleated TiC particles in the liquid phase and (4) precipitation of TiC γ-Ni extended solid solution.