Ti-48(at%)Al包晶合金中β/α相的过冷形核  

Nucleation of β/α Phases in Undercooled Ti-48(at%)Al Peritectic Alloy

作　　者：李曼[1] 薛祥义[1] 胡锐[1] 张铁邦[1] 钟宏[1] 李金山[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：《航空材料学报》2012年第2期1-7,共7页Journal of Aeronautical Materials

基　　金：国家重点基础研究发展计划项目(2011CB610404);国家自然科学基金项目(51001086);西北工业大学基础研究基金项目(JC20100207)

摘　　要：采用电磁悬浮熔炼的深过冷凝固技术实现了Ti-48(at%)Al合金的深过冷,获得的最大过冷度为295K。采用红外测温仪记录实验过程的温度变化数据,OM技术观察不同过冷度下凝固合金的显微组织,结合深过冷凝固过程中的再辉行为分析了该合金的非平衡凝固路径。运用负熵模型、经典形核理论及瞬态形核理论,研究了Ti-48(at%)Al包晶合金中初生相与次生相的形核与过冷度之间的关系。通过对该合金熔体的β(bcc)相和α(hcp)相的临界形核功、稳态形核率、形核孕育时间和瞬态形核率的计算,并结合实验结果对β,α两相的形核进行了综合分析。结果表明,在～10K/s的较低冷速情况下,在整个过冷度(≤295K)范围内β(bcc)相总能作为初生相首先形核。The Ti-48（at%）Al peritectic alloy was solidified at various bulk undercooling using electromagnetic levitation method.The maximum undercooling of the alloy melt was up to 295K.Detailed thermal histories were acquired during experiments using optical pyrometry.The solidification microstructures were investigated by OM.Solidification and other high-temperature transformation pathways were deduced from the thermal data and microstructural analysis.The dependence of nucleation between the primary phase and the secondary phase on the undercooling was identified by analyzing the recalescence behaviour and microstructure,and investigated systematically by using the classical solidification theory,the negentropic model and the transient nucleation theory.The interfacial critical work of nucleation,steady state nucleation rates,incubation time and time dependent nucleation rate of two phases β（bcc） phase and α（hcp） phase were calculated,and the calculated results were analyzed by comparing with the experimental data.The results are as fellows： β phase is always prior to nucleate from all undercooled（≤295K） melt below the cooling rate ~10K/s.

关 键 词：形核 过冷度 再辉 初生相 次生相 

分 类 号：TG146.2[一般工业技术—材料科学与工程]