深过冷Al_(46.2)Fe_(36.6)Ti_(17.2)包共晶合金的快速凝固及组织演变  

Rapid Solidification and Microstructure Evolution of Undercooled Al_(46.2)Fe_(36.6)Ti_(17.2) Quasiperitectic Alloy

作　　者：鲁晓宇[1] 吴静毅 翟薇[1] 

机构地区：[1]西北工业大学理学院,陕西西安710072 [2]西安理工大学高等技术学院,陕西西安710109

出　　处：《铸造技术》2016年第3期476-480,共5页Foundry Technology

基　　金：国家自然科学基金资助项目(51171153;51201136)

摘　　要：采用落管无容器处理技术实现了Al_（46.2）Fe_（36.6）Ti_（17.2）三元包共晶合金的深过冷与快速凝固,获得直径为130~1 150μm的合金粒子,其过冷度范围为202~30 K。研究发现,在自由落体条件下,合金熔体在快速凝固过程中呈现显著的溶质截留效应,包共晶转变进行得不彻底,凝固组织中包含Fe_2Ti相、Fe Al相和τ_2相,其中Fe_2Ti相为初生相,组织呈现枝晶形貌,Fe Al相和τ_2相形成层片状包共晶组织。随着液滴直径的减小,冷却速率增加,过冷度增大,凝固组织中初生Fe_2Ti相的形貌由粗大枝晶逐渐变为细碎枝晶,一次枝晶轴长度与粒子直径呈线性减小关系;包共晶组织由长条状层片变为球状胞,并且层片间距呈指数型减小。U ndercooled Al_（46.2）Fe_（36.6）Ti_（17.2）quasiperitectic alloy was rapidly solidified in the form of 130~1150 μm diameter droplets inside drop tube, and the maximum undercooling of 202 K（0.14 TL） was achieved. The rapid solidification route is characterized by the primary growth of Fe_2 Ti and the following quasiperitectic transformation of L＋Fe_2Ti→Fe Al＋τ_2. The solidification microstructure contains Fe_2 Ti, Fe Al and τ_2phases. The primary Fe_2 Ti phase solidify into dendrite morphology,while Fe Al and τ_2phases grow into lamellar structure. As droplet diameter decreases, the primary Fe_2 Ti phase transforms from course into fine dendrites, whose average size decreases linearly. Meanwhile, the lamellar spacing of（Fe Al＋τ_2）quasiperitectic structure reduces exponentially with the decrease of the droplet diameter.

关 键 词：快速凝固 落管 包共晶 组织演变 

分 类 号：TG131[一般工业技术—材料科学与工程]