| Related citation: | Xiaoyu Chen,Hongze Fang,Qi Wang,Ruirun Chen,Hongsheng Ding,Yanqing Su,Jingjie Guo.Effects of Rapid Cooling Rate on Microstructure Formation and Microhardness of Binary Ti-44Al Alloy[J].Journal of Harbin Institute Of Technology(New Series),2020,27(3):225-232.DOI:10.11916/j.issn.1005-9113.20042. |
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| Author Name | Affiliation | | Xiaoyu Chen | School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China
School of Electromechanic Engineering, Qingdao University, Qingdao 266071, Shandong, China | | Hongze Fang | School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China | | Qi Wang | School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China | | Ruirun Chen | School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China | | Hongsheng Ding | School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China | | Yanqing Su | School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China | | Jingjie Guo | School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China |
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| Abstract: |
| In order to refine microstructure grains and improve mechanical properties of TiAl alloys, Ti44Al (at.%) alloy was rapidly solidified by melt spinning under different cooling rates. Microstructure and microhardness of the alloy before and after rapid solidification were investigated. XRD results show that the ratio of α2 phase in binary alloy increased with the cooling rates, which is caused by more α phases directly transforming to α2 phases. Grain morphology changed from long dendrite to the mixture of equiaxed and dendrite to equiaxed with the increase of cooling rates. The grain size was refined from 200-600 μm of as-cast to 18 μm of the alloy cooled at 4.9×105K/s, which is caused by the undercooling induced from rapid solidification. Lamellar spacing was decreased from 4.5 μm of as-cast to 1.1 μm by rapid solidification. With the increase of cooling rate, the content of α 2 phase increased and γ phase decreased gradually. Rapid solidification can reduce the segregation of elements. The microhardness was improved from 247 HV to 556 HV, which results from grain refinement strengthening, reduction of lamellar spacing, and more content of α2 phase. |
| Key words: Ti-44Al alloy microstructure microhardness melt spinning solidification path |
| DOI：10.11916/j.issn.1005-9113.20042 |
| Clc Number:TG146 |
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| Descriptions in Chinese: |
| 快速冷却速率对Ti-44Al合金组织和显微硬度的影响 陈晓宇1,2，方虹泽1，王琪1，陈瑞润1，丁宏升1，苏彦庆1，郭景杰1 （1. 哈尔滨工业大学 材料科学与工程学院，哈尔滨 150001； 2. 青岛大学 机电工程学院，山东 青岛 266071） 中文说明：为细化TiAl合金的显微组织与晶粒，提高其力学性能，采用甩带快速凝固方法在不同冷却速率条件下制备了Ti-44Al（at.%）合金，研究了铸态与快速凝固合金的显微组织和显微硬度。XRD测试结果表明，合金中α2相含量随着冷却速率增加而增加，这是由于高的凝冷却率导致α相直接转变为α2相。随着冷却速率的增加，晶粒形态首先由树枝晶转变为等轴晶和树枝晶混合的组织，而后转变为等轴晶。经快速凝固制备后，合金晶粒尺寸由铸态的200-600 μm降低到快速凝固的18 μm。片层厚度由铸态的4.5 μm降低到快速凝固的1.1 μm。随着冷却速率的增加，α2相含量逐渐增加，γ相含量逐渐减少，并且快速凝固可以降低基体中元素偏析。快速凝固的合金晶粒细化，片层厚度降低，并且α2相含量增加，这导致显微硬度由铸态的247 HV提高到快速凝固的556 HV。 关键词：Ti-44Al合金，显微组织，显微硬度，甩带快速凝固，凝固路径 |
