摘要
采用扫描电镜和电子探针分别观察了用水冷铜坩埚磁悬浮、Drop casting法所制备样品及磁悬浮法大铸锭样的微观组织。结果发现:磁悬浮法大铸锭的微观组织存在明显的宏观铸造缺陷,基本没有微观缺陷;其微观组织中有明显的晶界,晶界上有块状的初生β(B2)相;其微观组织具有典型的片层状特征。Drop casting法铸锭的组织特征为:显微缩松;晶界不明显;无块状的晶界初生β(B2)相,但存在着白色的网状组织;没有明显的片层状组织。磁悬浮法大锭重熔样的微观组织特征与Drop casting法铸锭的组织特征相似。水冷铜坩埚磁悬浮与Drop casting法这两种铸造方法所得的微观组织不同,其成因跟合金的冷却速率有关,在特定的条件下两者之间可以发生相互转变。在1 450℃保温2 h后淬冰盐水后,磁悬浮法铸锭微观组织的转变成与Drop casting法微观组织相似的组织。磁悬浮法大锭样在非自耗电弧炉上重熔时,其微观组织与Drop casting锭的组织很相似,关键在于两者的冷却速率更为接近。
The microstractures of ingots produced by magnetic levitation cold crucible technique, drop casting technique and re-melting from magnetic levitation sample were observed under scanning electron microscope and electron probe. The results show that the samples produced by magnetic levitation cold crucible technique have apparent casting macro-defect and there is almost not any micro-defect. There is apparent grainboundary in the magnetic levitation ingot and there is primary block β（B2） phase. The lamella of Ti-45Al-7Nb-0.4W-0.15B alloy is perfect. The samples produced by drop casting have micro-pores. There are not any apparent grainboundary and any primary block β（B2） phase, but there is white net. There is not lamella in the ingot. The differences between magnetic levitation cold crucible technique and drop casting technique result from cooling velocity of molten and they can transform reciprocally under the specific condition. The microstructure of ingot produced by magnetic levitation likes that produced by drop casting after being kept at 1 450 ℃ for 2 h then quenched in iced salt solution. The microstractural features of drop casting cast are similar with those of re-melting cast of magnetic levitation ingot. Because they are very close in cooling velocity.
出处
《中国有色金属学报》
EI
CAS
CSCD
北大核心
2008年第4期643-650,共8页
The Chinese Journal of Nonferrous Metals
