激光悬浮区熔定向凝固Al_2O_3/YAG/ZrO_2三元过共晶合金的微观组织  

MICROSTRUCTURE OF Al_2O_3/YAG/ZrO_2 HYPEREUTECTIC ALLOY DIRECTIONALLY SOLIDIFIED BY LASER FLOATING ZONE METHOD

作　　者：宋衎[1] 张军[1] 贾晓娇[1] 苏海军[1] 刘林[1] 傅恒志[1] 

机构地区：[1]西北工业大学凝固技术国家重点实验室,西安710072

出　　处：《金属学报》2012年第2期220-226,共7页Acta Metallurgica Sinica

基　　金：国家自然科学基金项目51002122和50772090;陕西省自然科学基金项目2010JQ6005;航空科学基金项目2010ZF53064;西北工业大学基础研究基金项目G9KY1016;西北工业大学材料学院"新人新方向"基金项目09XE0104-5;凝固技术国家重点实验室自主课题项目76-QP-2011;高等学校学科创新引智计划项目B08040资助~~

摘　　要：利用自行研制的激光悬浮区熔设备制备了Al_2O_3/YAG/ZrO_2三元过共晶自生复合材料.在过共晶成分下获得了不含初生相的全共晶层片状组织.详细分析了固/液界面形貌形成原因,并由界面形貌出发阐述了Al_2O_3/YAG/ZrO_2三元过共晶组织织构化趋势.结果表明,低凝固速率下,三元过共晶成分下层片间距大于三元共晶成分下层片间距,而在高凝固速率下则相反,这主要是由于ZrO_2的加入影响了体系的传热及传质条件,通过经典非规则共晶模型综合分析了传输条件对层片间距的影响.过共晶平均层片间距(λ_(av))与凝固速率(V)满足λ_(av)V^(0.5)=14.7μm^(1.5)·s^(-0.5),符合JH模型.对于激光加工中经常出现的带状组织形成机理也进行了讨论.Due to the excellent high temperature mechanical properties,Al203/YAG/Zr02 ternary eutectic in situ composite is considered to be a promising candidate for the material,replace- ment for nickel based superalloy,of new generation aero space engine turbine blade.The directionally solidified A^Os/YAG/ZrO^ hypereutectic ceramics are prepared with recently developed laser float- ing zone melting（LFZM） apparatus.Full eutectic lamellar microstructure,free of primary phase, was obtained with hypereutectic composition.The formation of solid/liquid interface morphology was analyzed in detail.The microstructure texture tendency was explained by combination with interface morphology.The experimental result indicates that,just as the prediction of JH model,av- erage spacing of hypereutectic（Aav） agrees with the inverse-square-root dependence on solidification rate（V） according to Aavl^°＇5=14.7 /um1,5-s＂0＇5.In lower solidification rate,the lamellar spacing of hypereutectic is higher than that of eutectic composition,but the situation reverses in higher rate. The main reason of such phenomenon is that the addition of ZrO_2 effects the thermal and solute transformation in the melt.The influence of transformation condition on lamellar spacing was analyzed synthetically by using classical irregular growth model.The formation mechanism of banded microstructure,often observed in laser zone melted solidification processing,was also discussed.

关 键 词：Al_2O_3/YAG/ZrO_2 过共晶 固/液界面 组织 

分 类 号：TG142[一般工业技术—材料科学与工程]