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为了调控激光沉积修复BT20钛合金的组织,提高其力学性能,将旋转磁场引入到激光修复系统中,考察了不同磁场强度下修复试样的组织和力学性能。结果显示,修复区和基体形成了致密冶金结合,修复区为α/β片层组织,硬度分布从基材到修复区依次提高;在一定范围内,磁场强度越强,α片层长/径比越小,片层组织越细密,修复区硬度越大,HV0.1可达4.4 GPa。表明磁场搅拌减轻了β晶溶质富集,使α片层析出的驱动力减小,需要在更大过冷度下析出,而过冷度的增加,导致形核率的增大,最终导致α层片细化,从而提高沉积层的力学性能。
In order to control the microstructure and mechanical properties of BT20 titanium alloy by laser deposition, the rotating magnetic field was introduced into the laser repair system, and the microstructure and mechanical properties of the repaired samples under different magnetic field strengths were investigated. The results show that the repair area and the matrix form a dense metallurgical bond, the repair area is α / β lamellar structure, and the hardness distribution increases from the base material to the repair area in turn. Within a certain range, the stronger the magnetic field strength, the longer the length / The smaller the ratio, the more dense the lamellar structure, repair the greater the hardness, HV0.1 up to 4.4 GPa. It shows that magnetic field agitates to reduce the β-solute enrichment and reduce the driving force for the precipitation of α-sheet, which needs precipitation under a greater degree of undercooling. The increase of undercooling results in the increase of nucleation rate, α layer thinning, thereby enhancing the mechanical properties of the deposited layer.