(山東科技大學(xué) 材料科學(xué)與工程學(xué)院，青島 266590)
摘 要: 利用直流電弧原位冶金技術(shù)制備WpC-Fe復(fù)合材料，通過物相分析、顯微組織觀察和硬度測試，研究非平衡凝固W2C的原位生成機(jī)制、形態(tài)演變以及含量和形貌對材料硬度的影響。結(jié)果表明：W和C原位反應(yīng)時，熔池溫度高于1652K，W2C比WC更易生成。直流電弧高溫熔池非平衡凝固過程中，W2C的生長機(jī)制由小平面晶變?yōu)榉切∑矫婢В饾u偏離由晶體結(jié)構(gòu)決定的六次等軸花狀晶初生形貌，以平行連生的方式生長為定向枝晶。W2C的顯微硬度低于WC的，由于受到形貌的影響，等軸花狀晶的硬度(1993 HV0.2)明顯高于定向枝晶的(1536HV0.2)；工作電流由600A增到1000A時，復(fù)合材料中W2C的生成量增加，宏觀硬度由84HRA下降為78HRA。
關(guān)鍵字: 非平衡凝固；W2C；原位反應(yīng)；生長形態(tài)；硬度
（College of Materials Science and Engineering, Shandong University of Science and Technology, Qingdao 266590, China）
Abstract: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.
Key words: non-equilibrium solidification; W2C; in situ reaction; growth morphology; hardness
