激光表面快凝下Nd_(13.5)Fe_(79.75)B_(6.75)过包晶合金的组织演化  

Microstructure evolution of Nd_(13.5)Fe_(79.75)B_(6.75) peritectic alloy under laser rapid solidification

作　　者：吕海燕[1] 李双明[1] 钟宏[1] 刘林[1] 邹光荣[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：《中国有色金属学报》2009年第2期322-327,共6页The Chinese Journal of Nonferrous Metals

基　　金：国家自然科学基金项目(50395102);教育部新世纪优秀人才支持计划资助项目(NCET-07-0692)

摘　　要：利用激光表面快速熔凝技术对Nd13.5Fe79.75B6.75过包晶合金的凝固组织及其变化规律进行研究。结果表明:当扫描速度大于2mm/s时,包晶反应(γ+L→T1)被抑制,包晶T1相可直接从液相中析出(L→T1)。根据最高界面生长温度判据及KGT模型计算了T1相领先析出的临界生长速度为0.34mm/s,理论预测值略小于实验确定值;另在100～500mm/s扫描速度范围内观测到粗胞晶→细胞晶→平界面的不同凝固形态的高速带状组织,理论预测此合金形成高速带状组织的速度范围为148～7800mm/s,理论预测下限值与实验结果吻合较好。Laser rapid solidification experiments were performed on Nd13.5Fe79.75B6.75 hyperperitectic alloy to investigate microstructure evolution. The results show that at scanning velocity higher than 2 mm/s, peritectic T1 phase directly precipitates from the liquid instead of by peritectic reaction. Using KGT model and the maximum growth temperature criterion, critical velocity for the transition from primary γ-Fe phase to Tl phase is calculated to be 0.34 mrn/s, which approaches the experimental Value of 2 mm/s. High velocity banding structure, showing oscillatory plane front and cellular microstructures, is firstly detected in Nd13.5Fe79.75B6.75 peritectic alloys. The growth velocity for banding structure is deduced to be in the range of 100-500 mrn/s. The experimental appearance of the banding structure agrees well with the theoretical prediction.

关 键 词：Nd13.5Fe79.75B6.75 包晶合金 激光表面快凝 相转变:带状组织 

分 类 号：TG132.32[一般工业技术—材料科学与工程]