直流电弧原位冶金制备粗晶碳化钨块体复合材料

Coarse-grain bulk WC composites prepared by direct current arc in-situ metallurgy

利用直流电弧原位冶金技术制备粗晶碳化钨块体复合材料,并利用X射线衍射仪、电子探针等对其物相组成、微观组织、W与C反应过程和WC生长形态演变机制进行研究。结果表明:碳化钨复合材料的主要硬质相为WC和W2C;当自耗电极长度增加时,WC含量降低,但晶粒尺寸增大,最大晶粒尺寸约为100μm。在原位冶金过程中,W和C元素通过溶解进入熔池发生扩散反应,逐步形成W2C和WC。WC生长形态由六棱柱演变为三棱柱,生长方式为小平面晶体台阶侧向长大;当达到临界过冷度时,WC晶粒迅速生长。

Coarse-grain bulk WC composites were prepared by direct current arc in-situ metallurgy. The examination of phase composition and microstructure for the materials, reaction process of W and C as well as transformation mechanism for WC morphologies was carried out by X-ray diffractometry and electron probe micro-analysis. The results show that WC and W2C are the main hard phases in the composites. Furthermore, the WC content decreases but the grain sizes of WC increase with increasing the length of consumable electrode, and the largest WC grains can reach about 100 μm. During the process of in-situ metallurgy, W and C dissolve and interdiffuse in the molten pool. As a result, W2C and WC form successively. The WC growth morphology is triangular prism that transforms from hexangular prism, and the growth pattern of WC is lateral growth layer by layer of the facet crystals. The WC grains can grow rapidly when undercooling reaches the critical value.