非平衡凝固W_2C的原位生长机理及硬度分析
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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。
W_pC-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 W_2 C as well as the influence of content and shape of W_2 C on hardness were also carried out. The results show that, when the temperature of molten pool over 1652 K, W_2 C 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 W_2 C 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 W_2 C is lower than that of WC, and influenced by shape. 1993 HV_(0.2) of the equiaxed dendrite is higher significantly than 1536HV_(0.2) of the directional dendrite. As the current increasing from 600 A to 1000 A, the W_2 C content increases, and the hardness of materials decreases to 78 HRA from 84 HRA.
W_pC-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 W_2 C as well as the influence of content and shape of W_2 C on hardness were also carried out. The results show that, when the temperature of molten pool over 1652 K, W_2 C 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 W_2 C 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 W_2 C is lower than that of WC, and influenced by shape. 1993 HV_(0.2) of the equiaxed dendrite is higher significantly than 1536HV_(0.2) of the directional dendrite. As the current increasing from 600 A to 1000 A, the W_2 C content increases, and the hardness of materials decreases to 78 HRA from 84 HRA.
引文
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[14]LI Jian-nan,LI Hui-qi,WANG Mei,WANG Shu-feng,JI Qiang,LI Min,CHI Jing.Applications of WC-based composites rapid synthesized by consumable electrode in-situ metallurgy to cutting pick[J].International Journal of Refractory Metals and Hard Materials,2012,35:132-137.
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[21]ZHONG Min-lin,LIU Wen-jin,ZHANG Yu,ZHU Xiong-feng.Formation of WC/Ni hard alloy coating by laser cladding of W/C/Ni pure element powder blend[J].International Journal of Refractory Metals and Hard Materials,2006,24:453-460.
[22]POWELL G L F,CARLSON R A,RANDLE V.The morphology and microtexture of M7C3 carbides in Fe-Cr-C and Fe-Cr-C-Si alloys of near eutectic composition[J].Journal of Materials Science,1994,29(18):4889-4896.
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[24]DMITRII V S,IGOR R S,ALEXANDER L I.Structural,electronic properties and stability of tungsten mono-and semi-carbides:A first principles investigation[J].Journal of Physics and Chemistry of Solids,2009,70(1):64-71.
[25]胡汉起.金属凝固原理[M].北京:机械工业出版社,2000.HU Han-qi.Fundamentals of metal solidification[M].Beijing:China Machine Press,2000.
[2]王建升,张占哲,闫镇威,李刚,唐明奇,冯在强.电火花沉积WC-4Co复合层界面行为[J].中国有色金属学报,2014,24(11):2849-2855.WANG Jian-sheng,ZHANG Zhan-zhe,YAN Zhen-wei,LI Gang,TANG Ming-qi,FENG Zai-qiang.Interface behavior of WC-4Co coating by electro-spark deposition[J].The Chinese Journal of Nonferrous Metals,2014,24(11):2849-2855.
[3]王群,屈帮荣,唐曌肸,熊浩奇.超音速火焰喷涂碳化钨-钴涂层磨粒磨损行为[J].中国有色金属学报,2015,25(7):1920-1928.WANG Qun,QU Bang-rong,TANG Zhao-xi,XIONG Hao-qi.Abrasive wear behavior of WC-Co coating deposited by high velocity oxygen flame process[J].The Chinese Journal of Nonferrous Metals,2015,25(7):1920-1928.
[4]OBADELE B A,OLUBAMBI P A,JOHNSON O T.Effects of Ti C addition on properties of laser particle deposited WC-Co-Cr and WC-Ni coating[J].Transactions of Nonferrous Metals Society of China,2013,23(12):3634-3642.
[5]HOMG Sheng,WU Yu-ping,WANG Bo,ZHENG Yu-gui,GAO Wen-wen,LI Gai-ye.High-velocity oxygen-fuel spray parameter optimization of nanostructured WC-10Co-4Cr coatings and sliding wear behavior of the optimized coating[J].Materials and Design,2014,55:286-291.
[6]HE Long,TAN Ye-hua,TU Yi-qiang,ZHANG Zhong-wei.Microstructure and tribological properties of WC-Ce O2/Ni-base alloy composite coatings[J].Rare Metal Materials and Engineering,2014,43(4):823-829.
[7]LIU De-jian,CHEN Yan-bin,LI Li-qun,LI Fu-qun.In situ investigation of fracture behavior in monocrystalline WCp-reinforced Ti-6Al-4V metal matrix composites produced by laser melt injection[J].Scripta Materialia,2008,59:91-94.
[8]刘发兰,赵树森,高文焱,周春阳,王奕博,林学春.基材属性对Ni60A-WC激光熔覆涂层性能的影响[J].中国有色金属学报,2014,24(5):1319-1326.LIU Fa-lan,ZHAO Shu-sen,GAO Wen-yan,ZHOU Chun-yang,WANG Yi-bo,LIN Xue-chun.Effect of substrate on Ni60A-WC laser cladding coatings[J].The Chinese Journal of Nonferrous Metals,2014,24(5):1319-1326.
[9]WANG Qun,ZHANG Shi-ying,CHENG Ying-liang,XIANG Jing,ZHAO Xin-qi,YANG Gui-bin.Wear and corrosion performance of WC-10Co4Cr coatings deposited by different HVOF and HVAF spraying processes[J].Surface&Coatings Technology,2013,218:127-136.
[10]袁有录,李铸国.Ni60A+WC增强梯度涂层中WC的溶解与碳化物的析出特征[J].材料工程,2013(11):12-25.YUAN You-lu,LI Zhu-guo.Dissolving and precipitating characteristics of WC and carbides in the Ni60A+WC graded coating[J].Journal of Materials Engineering,2013(11):12-25.
[11]张宇,钟敏霖,刘文今.送粉激光熔覆合成制备WC/Ni硬质合金涂层及其耐磨性[J].金属热处理,2005,30(11):1-5.ZHANG Yu,ZHONG Min-lin,LU Wen-jin.WC/Ni cemented carbide coating and its wear resistance synthesized by laser powder feeding cladding[J].Heat Treatment of Metals,2005,30(11):1-5.
[12]迟静,李惠琪,王淑峰,李敏,李建楠,王梅,高旭杰.直流电弧原位冶金制备粗晶碳化钨块体复合材料[J].中国有色金属学报,2013,23(5):1262-1268.CHI Jing,LI Hui-qi,WANG Shu-feng,LI Min,LI Jian-nan,WANG Mei,GAO Xu-jie.Coarse-grain bulk WC composites prepared by direct current arc in-situ metallurgy[J].The Chinese Journal of Nonferrous Metals,2013,23(5):1262-1268.
[13]王淑峰,李惠琪,迟静,李敏,柴禄,许慧.等离子原位冶金复合碳化钨合金组织特性与结晶机理研究[J].材料工程,2011(8):72-76.WANG Shu-feng,LI Hui-qi,CHI Jing,LI Min,CHAI Lu,XU Hui.Microstructure and crystallization mechanism of composite WC alloy produced by plasma in-situ metallurgy[J].Journal of Materials Engineering,2011(8):72-76.
[14]LI Jian-nan,LI Hui-qi,WANG Mei,WANG Shu-feng,JI Qiang,LI Min,CHI Jing.Applications of WC-based composites rapid synthesized by consumable electrode in-situ metallurgy to cutting pick[J].International Journal of Refractory Metals and Hard Materials,2012,35:132-137.
[15]周玉.材料分析方法[M].北京:机械工业出版社,2004.ZHOU Yu.Materials analysis methods[M].Beijing:China Machine Press,2004.
[16]KURLOV A S,GUSEV A I.Neutron and X-ray diffraction study and symmetry analysis of phase transformations in lower tungsten carbide W2C[J].Physcial Review B,2007,76:1-16.
[17]KURLOV A S,GUSEV A I.Phase equilibria in the W-C system and tungsten carbides[J].Russian Chemical Reviews,2006,75(7):617-636.
[18]BERGER L M,SAARO S,NAUMANN T,KA?PAROVA M,ZAHáLKA F.Influence of feedstock powder characteristics and spray processes on microstructure and properties of WC-(W,Cr)2C-Ni hardmetal coatings[J].Surface and Coatings Technology,2010,205(4):1080-1087.
[19]LAY S,ALLIBERT C H,CHRISTENSEN M,WAHNSTROM G.Morphology of WC grains in WC-Co alloys[J].Materials Science and Engineering A,2008,486:253-261.
[20]LAY S,DONNADIEU P,LOUBRADOU M.Polarity of prismatic facets delimiting WC grains in WC-Co alloys[J].Micron,2010,41:472-477.
[21]ZHONG Min-lin,LIU Wen-jin,ZHANG Yu,ZHU Xiong-feng.Formation of WC/Ni hard alloy coating by laser cladding of W/C/Ni pure element powder blend[J].International Journal of Refractory Metals and Hard Materials,2006,24:453-460.
[22]POWELL G L F,CARLSON R A,RANDLE V.The morphology and microtexture of M7C3 carbides in Fe-Cr-C and Fe-Cr-C-Si alloys of near eutectic composition[J].Journal of Materials Science,1994,29(18):4889-4896.
[23]叶大伦,胡建华.实用无机热力学数据手册[M].北京:冶金工业出版社,2002.YE Da-lun,HU Jian-hua.Practical inorganic thermodynamics data handbook[M].Beijing:Metallurgical Industry Press,2002.
[24]DMITRII V S,IGOR R S,ALEXANDER L I.Structural,electronic properties and stability of tungsten mono-and semi-carbides:A first principles investigation[J].Journal of Physics and Chemistry of Solids,2009,70(1):64-71.
[25]胡汉起.金属凝固原理[M].北京:机械工业出版社,2000.HU Han-qi.Fundamentals of metal solidification[M].Beijing:China Machine Press,2000.