及其晶粒细化效果
(1． 华中科技大学 模具技术国家重点实验室，
武汉 430074；
2． 武汉理工大学 材料科学与工程学院，武汉 430070)
摘 要: 采用自蔓延高温合成（SHS）技术直接合成了Al-80%TiC和Al-50%TiC晶粒细化剂。 研究了这两种细化剂的相组成、结构及对工业纯铝的晶粒细化效果，并与商用Al-5Ti-1B细化剂进行了对比。结果表明：合成的细化剂由TiC和α-（Al）两相组成，TiC粒子的尺寸和分布对细化剂的晶粒细化效果有显著影响。Al-80%TiC细化剂中TiC粒子尺寸较大（2～5μm）且呈聚集成团分布，其晶粒细化效果较差。合成的Al-50%TiC细化剂的晶粒细化效果略优于Al-5Ti-1B细化剂。加入0.1%的该细化剂就能使凝固试样的结构由粗大的柱状晶转变成细小的等轴晶（平均晶粒尺寸120μm），且这种晶粒细化效果可保持90min。SEM和TEM分析显示，Al-50%TiC细化剂中原位合成的TiC粒子具有亚微米尺寸（0.4～0.9μm），且在高温铝液中具有较强的稳定性，从而赋予该细化剂良好的晶粒细化效果和强的抗晶粒细化衰退能力。
关键字: 自蔓延高温合成；Al-TiC晶粒细化剂；工业纯铝；晶粒细化
performances for commercially pure aluminum
（1. State Key Lab of Die Technology,
Huazhong University of Science & Technology,
Wuhan 430074, China;
2. School of Materials Science and Engineering,
Wuhan University of Technology,
Wuhan 430070, China）
Abstract:Al-80%TiC and Al-50%TiC grain refiners were directly synthesized by self-propagating high-temperature synthesis (SHS) technology. The phase components and microstructures of the synthesized grain refiners were examined by XRD and SEM, and their grain refining performances for commercially pure aluminum were also evaluated and compared with commonly used Al-5Ti-1B grain refiner. The results show that the SHS grain refiners consist of TiC and α-(Al), and that the size and distribution of TiC particles have significant influence on the grain refining properties of the SHS grain refiners. Al-80%TiC has poor grain refining effect because of coarser size (2～5μm) and agglomeration of the synthesized TiC particles, whereas Al-50%TiC exhibits higher grain refining performance than Al-5Ti-1B . The addition of SHS Al-50%TiC grain refiner to the molten aluminum in the amount of 0.1% might transform the structure of the solidified samples from coarse columnar grains to fine equiaxed grains (average grain size 120μm), and this grain refining effect could be maintained for 90min at 1003K. SEM and TEM examinations show that submicron (0.4～0.9μm) TiC particles in SHS Al-50%TiC grain refiner exhibit high thermodynamic stability in liquid aluminum, thereby affording the grain refiner excellent grain refining performance and high resistance to grain refining fading.
Key words: SHS; Al-TiC grain refiner; commercially pure aluminum; grain refinement
