Li Yong, Xu Wei, Su Qing, Wang Qiulin
Chengdu Aeronautic Polytechnic, Chengdu 610100, China.
Material Corrosion and Protection Key Laboratory of Sichuan Province, Zigong 643000, China.
ACS Omega. 2024 Nov 7;9(46):46176-46191. doi: 10.1021/acsomega.4c06757. eCollection 2024 Nov 19.
The effect of an alternating electromagnetic field on the microstructure and properties of the Ti-Al coating on the titanium alloy surface is studied. The Ti-Al coating is prepared on the surface of titanium alloy by using an alternative electromagnetic field assisted by high temperature thermal diffusion. The preparation method is simple and easy to operate. The microstructure and element distribution of the coating under different magnetic field intensities are analyzed. The mechanism of improving the comprehensive properties of coatings by alternative electromagnetic fields with different intensities is discussed. The test results show that the outer surface of TA titanium alloy diffused at 850 °C without magnetic field is not smooth, the quality is poor, and internal structure cracks appear. No obvious cracks are found in the coating microstructure of 850 °C diffused by a magnetic field with 10 A current intensity, but there are still some holes. A large number of holes and cracks appear in the coating microstructure with 850 °C diffusion under the magnetic field with 15 A current intensity; mostly longitudinal cracks are perpendicular to the interface and penetrating through the interface, which may be caused by the thermal effect of the magnetic field. The coating diffused under the magnetic field of 20 A current intensity has good overall quality, good bonding with the substrate, relatively flat interface, dense, uniform, and fine structure, and no obvious cracks and holes are found. The main phases are TiAl, TiAl and elemental Al, and TiAl has obvious texture, with an average equivalent diameter of 3.2 μm. TiAl has no obvious texture and has an average equivalent diameter of 2.2 μm. The electromagnetic stirring effect makes the strengthening phase in the coating more evenly distributed and reduces component segregation. With the increase of magnetic field intensity, the stress concentration and cracking sensitivity decrease and the migration distance of Ti atoms from the matrix to the coating direction increases. The interfacial hardness of the coating extends outward at first and then decreases, and the maximum hardness reaches 468.2 HV. The cracking sensitivity of the coating is reduced by the magnetic field, and the microstructure and properties of the coating are improved.
研究了交变电磁场对钛合金表面Ti-Al涂层微观结构及性能的影响。采用高温热扩散辅助交变电磁场在钛合金表面制备Ti-Al涂层。该制备方法简单易操作。分析了不同磁场强度下涂层的微观结构和元素分布。探讨了不同强度交变电磁场提高涂层综合性能的机理。试验结果表明，850℃无磁场扩散的TA钛合金外表面不平整，质量较差，出现内部结构裂纹。电流强度为10A的磁场在850℃扩散的涂层微观结构中未发现明显裂纹，但仍存在一些孔洞。电流强度为15A的磁场在850℃扩散的涂层微观结构中出现大量孔洞和裂纹；大多纵向裂纹垂直于界面并贯穿界面，这可能是由磁场的热效应引起的。电流强度为20A的磁场扩散的涂层整体质量良好，与基体结合良好，界面相对平整，致密、均匀且组织细小，未发现明显裂纹和孔洞。主要相为TiAl、TiAl和元素Al，TiAl有明显织构，平均等效直径为3.2μm。TiAl无明显织构，平均等效直径为2.2μm。电磁搅拌作用使涂层中的强化相分布更均匀，减少了成分偏析。随着磁场强度的增加，应力集中和开裂敏感性降低，Ti原子从基体向涂层方向的迁移距离增加。涂层的界面硬度先向外扩展后降低，最大硬度达到468.2 HV。磁场降低了涂层的开裂敏感性，改善了涂层的微观结构和性能。
