非平衡凝固W_2C的原位生长机理及硬度分析  

In-suit growth mechanism and hardness of W_2C under non-equilibrium solidification conditions

作　　者：迟静[1] 李惠琪[1] 王淑峰[1] 李敏[1] 吴杰[1] 李建楠[1] 赵健[1] CHI Jing LI Hui-qi WANG Shu-feng LI Min WU Jie LI Jian-nan ZHAO Jian(College of Materials Science and Engineering, Shandong University of Science and Technology, Qingdao 266590, Chin)

机构地区：[1]山东科技大学材料科学与工程学院,青岛266590

出　　处：《中国有色金属学报》2017年第3期555-562,共8页The Chinese Journal of Nonferrous Metals

基　　金：青岛市技术创新平台建设计划(14-7-2-42-gx);青岛经济技术开发区重点科技发展计划(2013-1-51);山东省自然科学基金(ZR2014EMM009)~~

摘　　要：利用直流电弧原位冶金技术制备W_pC-Fe复合材料,通过物相分析、显微组织观察和硬度测试,研究非平衡凝固W_2C的原位生成机制、形态演变以及含量和形貌对材料硬度的影响。结果表明:W和C原位反应时,熔池温度高于1652K,W_2C比WC更易生成。直流电弧高温熔池非平衡凝固过程中,W_2C的生长机制由小平面晶变为非小平面晶,逐渐偏离由晶体结构决定的六次等轴花状晶初生形貌,以平行连生的方式生长为定向枝晶。W_2C的显微硬度低于WC的,由于受到形貌的影响,等轴花状晶的硬度(1993 HV_(0.2))明显高于定向枝晶的(1536HV_(0.2));工作电流由600A增到1000A时,复合材料中W_2C的生成量增加,宏观硬度由84HRA下降为78HRA。WpC-Fe composites were successfully fabricated by direct current arc in-situ metallurgy. Through the examination of phase composition, microstructure and hardness for the resultant materials, the in-situ growth mechanism and morphology transformation for W2C as well as the influence of content and shape of W2C on hardness were also carried out. The results show that, when the temperature of molten pool over 1652 K, W2C is formed more easily than WC in the in-situ reaction between W and C. During the non-equilibrium solidification process, the growth mechanism of W2C transits from lateral growth to non-lateral growth, the morphology gradually deviates from the petal-like shape with hexagonal symmetry determined by crystal structure, and grows into directional dendrite with the pattern of parallel intergrowth. The microhardness of W2C is lower than that of WC, and influenced by shape. 1993 HV0.2 of the equiaxed dendrite is higher significantly than 1536HV0.2 of the directional dendrite. As the current increasing from 600 A to 1000 A, the W2C content increases, and the hardness of materials decreases to 78HRA from 84HRA.

关 键 词：非平衡凝固 W2C 原位反应 生长形态 硬度 

分 类 号：TB331[一般工业技术—材料科学与工程]