WC-Ni_3Al合金烧结过程WC晶粒生长行为的研究  

Growth Behavior of WC Grains in Ni_3Al Matrix during Liquid Phase Sintering

作　　者：张卫兵[1,2] 夏艳萍[1,2] 龙坚战[1,2] 伍文辉[1,2] 

机构地区：[1]硬质合金国家重点实验室,湖南株洲412000 [2]株洲硬质合金集团有限公司,湖南株洲412000

出　　处：《硬质合金》2014年第6期327-331,共5页Cemented Carbides

基　　金：国家重点基础研究发展计划(973计划)2012CB723906资助项目

摘　　要：本文以WC-36%Ni3Al(文中百分含量如无特殊说明,均为体积分数)合金体系为研究对象,采用传统粉末冶金方法制备出WC-36%Ni3Al和WC-36%Co复合材料,用带能谱分析的扫描电子显微镜观察试样腐蚀后的区域,用EDS检测粘结相的化学组成,采用透射电子显微镜在高倍条件下观察WC形貌特征,研究了2种不同粒度WC在Ni3Al液相基体中的晶粒长大行为。结果表明,在碳饱和条件下烧结后,粗细WC晶粒表面都出现了明显的刻面台阶;细粒度WC晶粒的异常长大得到抑制,这与WC在Ni3Al基体中的低溶解度有关。由于WC晶粒的两个惯习面具有不同的表面能,随着烧结时间的延长,粗粒度WC晶粒平均粒径不断增大且发生取向生长而形成了粗大的WC。Growth behavior of WC grains with two different sizes in the same liquid matrix has been studied in the WC-36%Ni3Al（volume fraction） system. Traditional powder metallurgy technology was used to manufacture the WC-36%Ni3Al composites and WC-36%Co composites. SEM imaging was performed on etched sections using a scanning electron microscope with an X-ray energy dispersive spectroscopy system. The chemical compositions of binder phase were characterized by energy dispersive spectroscopy. The high-magnification WC morphology was measured using transmission electron microscopy. The samples were sintered under a carbon saturated condition. The present investigation shows that surfaces of coarse WC grains and fine WC grains are strongly micro-faceted and stepped. The growth behavior of fine WC grain is affected by lower solubility of W in Ni3 Al matrix and the abnormal growth of WC grains is suppressed. With the increase of sintering time, the average size of the coarse WC grains increases continuously and very large oriented plate-like triangular prismatic WC grains appear, which is attributed to the difference in energy between the two families of prismatic planes.

关 键 词：晶粒长大 WC-Ni3Al 晶粒形貌 烧结 

分 类 号：TG135.5[一般工业技术—材料科学与工程] TF124.5[金属学及工艺—合金]