液态金属冷却定向凝固工艺下大尺寸高温合金铸件的显微组织分布  

Microstructure Distribution of Large Scale Directionally Solidified Casting Processed by Liquid Metal Cooling

作　　者：姜祥伟[1] 李辉[1] 楼琅洪[1] 

机构地区：[1]中国科学院金属研究所高温合金研究部,辽宁沈阳110016

出　　处：《铸造》2014年第9期883-886,共4页Foundry

摘　　要：采用液态金属冷却工艺,对大尺寸定向凝固镍基高温合金铸件的显微组织分布、变化规律进行研究。结果表明:随铸件远离冷却盘,冷却速率逐步降低;利用二次枝晶间距与冷却速率之间的定量关系,经计算得出距离冷却盘10 mm、100 mm、200 mm和300 mm位置的冷却速率分别为2 K/s、1 K/s、0.42 K/s和0.26 K/s。冷却速率的降低导致铸件不同位置的显微组织发生变化,包括枝晶组织发生粗化,MC碳化物由规则八面体形貌发展为汉字体形貌,显微缩松含量增加。冷却速率对枝晶组织的变化产生直接影响,而MC碳化物形貌和显微缩松含量变化主要由枝晶间距的变化而引起。The as-cast microstructure in different positions of a large scale directionally solidified casting prepared by liquid metal cooling （LMC） was studied by OM and SEM.The results show that cooling rate decreases gradually with the increasing of the distance of sampling position from the chill plate.According to the relationship between cooling rate and secondary dendrite arm spacing,cooling rate in the areas with different distances from the chill plate has been calculated.The cooling rate with distances of 10 mm,100 mm,200 mm and 300 mm from the chill plate is 2 K/s,1 K/s,0.42 K/s and 0.26 K/s,respectively.With cooling rate decreasing,primary and secondary dendrite arm spacing and area fraction of porosity increase and primary MC carbide evolved from an octahedral block appearance to Chinese-script morphology.The decreasing of cooling rate results in the increase of dendrite arm spacing directly,which has a significant effect on evolution of MC morphology and area fraction of dispersed shrinkage.

关 键 词：液态金属冷却 冷却速率 枝晶 MC碳化物 缩松 

分 类 号：TG132.3[一般工业技术—材料科学与工程] TG244[金属学及工艺—合金]