旋转磁场对无铅钎料组织及显微硬度的影响

Effect of rotary magnetic field on microstructure and microhardness of lead-free solder

为改善无铅钎料组织性能,研究了在0.125 T、1 250 r/min的情况下旋转磁场对Sn3.0Ag0.5Cu、Sn-9Zn钎料组织和显微硬度的影响.结果表明:旋转磁场作用对Sn3.0Ag0.5Cu、Sn-9Zn钎料的物相构成没有影响,但可使钎料构成相的尺寸、形状及分布发生明显变化,其中部分Ag3Sn相发生弯曲,富Zn相变为细小且分布呈一定的旋转状.与未经旋转磁场作用相比,磁场作用后Sn3.0Ag0.5Cu和Sn-9Zn钎料的显微硬度分别提高15.6%和10.2%,达到HV 24.5和HV 19.3.旋转磁场与感应电流间的Lorentz力具有驱动熔体随电磁场运动的趋势,将影响钎料组织凝固及其显微硬度.

In order to improve both microstructure and performance of lead-free solders, the effect of rotary magnetic field on the microstructure and microhardness of Sn3.0Ag0. 5Cu and Sn-9Zn solders was investigated with the magnetic field of 0. 125 T and 1 250 r/min. The results show that the rotary magnetic field has no influence on the phase constituent of Sn3.0Ag0. 5Cu and Sn-9Zn solders, but can significently change the size, shape and distribution of phases in the solders. Moreover, the bend of partial Ag3 Sn phase occurs, and the Zn-rich phase gets refined and distributes in certain rotational shape. Compared with the solders without imposing magnetic field, the microhardness of Sn3.0Ag0. 5Cu and Sn-9Zn solders subjected to rotary magnetic field increases 15. 6% and 10. 2%, and reaches 24. 5 and 19. 3 HV, respectively. The Lorentz force between the rotary magnetic field and induced current shows the tendency to drive the movement of molten solders with electromagnetic field, which will affect the solidification microstructure and microhardness of the solders.