Liu Yanhui, Ding Jieqiong, Qu Weicheng, Su Yu, Yu Zhishui
School of Materials Engineering, Shanghai University of Engineering Science, Shanghai 201620, China.
Materials (Basel). 2017 Mar 11;10(3):281. doi: 10.3390/ma10030281.
In this paper, a TiC reinforcement metal matrix composite coating is produced using nickel and graphite mixing powder on the surface ofTi-6Al-4V alloy by laser radiation. The microstructure of the coatings is investigated by XRD, SEM and EDS. Results show that most of the TiC phase is granular, with a size of several micrometers, and a few of the TiC phases are petals or flakes. At the cross-section of the coatings, a few special TiC patterns are found and these TiC patterns do not always occur at the observed cross-section. The even distribution of the TiC phase in the coatings confirms that the convection of the laser-melted pool leads to the homogenization of titanium atoms from the molten substrate, and carbon atoms from the preplace powder layer, by the mass transfer. The characteristics of the TiC pattern confirm that the morphology and distribution of the primary TiC phase could be influenced by convection. Two main reasons for this are that the density of the TiC phase is lower than the liquid melt, and that the primary TiC phase precipitates from the pool with a high convection speed at high temperature.
本文采用镍与石墨混合粉末，通过激光辐照在Ti-6Al-4V合金表面制备了TiC增强金属基复合涂层。利用X射线衍射仪（XRD）、扫描电子显微镜（SEM）和能谱仪（EDS）对涂层的微观结构进行了研究。结果表明，大部分TiC相呈颗粒状，尺寸为几微米，少数TiC相为花瓣状或片状。在涂层的横截面上，发现了一些特殊的TiC图案，且这些TiC图案并非总是出现在所观察的横截面上。TiC相在涂层中的均匀分布证实，激光熔池的对流通过传质作用使来自熔融基体的钛原子和来自预置粉末层的碳原子均匀化。TiC图案的特征证实，初生TiC相的形态和分布可能受对流影响。造成这种情况的两个主要原因是，TiC相的密度低于液态熔体，且初生TiC相在高温下以较高的对流速度从熔池中析出。
