Sang-Kyu Yoo, Ji-Won Kim, Cho-Long Lee, Myung-Hoon Oh, In-chul Choi
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After the brazing process, the microstructure of the interfacial area revealed seven distinct layers resulting from chemical reactions between the base metals and the filler metal. These reaction layers consisted of a Ni solid solution, intermetallic compounds (Ti3Al, TiNi2Al, Ti2Ni, FeNi), and borides (CrB, TiB2, FeB). To analyze the effect of brazing temperature on the relationship between the microstructure and mechanical properties at the interface of TiAl/HI-TEMP 820/SCM440H materials, conventional uniaxial tests and nanoindentation tests were performed. The measured nanohardness exhibited a significantly large distribution for each reaction layer, with the highest hardness values observed in the intermetallic compounds and borides layers. 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引用次数: 0
摘要
TiAl 合金具有较高的比强度、出色的高温成形性和疲劳强度,因此作为一种轻质耐热材料备受关注。然而,由于其单价高、室温延展性低,其应用受到了限制。为了克服这一问题,人们广泛采用了异种粘接材料。这包括使用各种异种结合技术,将脆性金属与具有优异塑性的低成本金属结合在一起。本研究采用真空钎焊工艺,在不同温度条件下制造了 TiAl/HI-TEMP 820/SCM440H 材料。钎焊过程结束后,界面区域的微观结构显示出七个不同的反应层,这些反应层是由基体金属和填充金属之间的化学反应产生的。这些反应层包括镍固溶体、金属间化合物(Ti3Al、TiNi2Al、Ti2Ni、FeNi)和硼化物(CrB、TiB2、FeB)。为了分析钎焊温度对 TiAl/HI-TEMP 820/SCM440H 材料界面微观结构和机械性能之间关系的影响,进行了传统的单轴测试和纳米压痕测试。测得的纳米硬度在各反应层中的分布明显较大,金属间化合物层和硼化物层的硬度值最高。此外,室温拉伸试验证实,高硬度和脆性金属间化合物层和硼化物层出现断裂。
Evaluation of Microstructure and Mechanical Properties of TiAl/HI-TEMP 820/ SCM440H Materials Manufactured through Vacuum Brazing according to Process Temperature
The TiAl alloy is attracting attention as a lightweight and heat-resistant material, because of its high specific strength, excellent high-temperature formability, and fatigue strength. However, its applications are limited by its high unit price and low room temperature ductility. To overcome this issue, dissimilarly bonded materials have been extensively employed. This involves joining a brittle metal to a low-cost metal that possesses excellent plasticity, using various dissimilar bonding techniques. In this study, TiAl/HI-TEMP 820/SCM440H materials were fabricated using a vacuum brazing process under different temperature conditions. After the brazing process, the microstructure of the interfacial area revealed seven distinct layers resulting from chemical reactions between the base metals and the filler metal. These reaction layers consisted of a Ni solid solution, intermetallic compounds (Ti3Al, TiNi2Al, Ti2Ni, FeNi), and borides (CrB, TiB2, FeB). To analyze the effect of brazing temperature on the relationship between the microstructure and mechanical properties at the interface of TiAl/HI-TEMP 820/SCM440H materials, conventional uniaxial tests and nanoindentation tests were performed. The measured nanohardness exhibited a significantly large distribution for each reaction layer, with the highest hardness values observed in the intermetallic compounds and borides layers. Additionally, room temperature tensile tests confirmed that fractures initiated in the highhardness and brittle intermetallic compounds and borides layers.
期刊介绍:
The Korean Journal of Metals and Materials is a representative Korean-language journal of the Korean Institute of Metals and Materials (KIM); it publishes domestic and foreign academic papers related to metals and materials, in abroad range of fields from metals and materials to nano-materials, biomaterials, functional materials, energy materials, and new materials, and its official ISO designation is Korean J. Met. Mater.