Control of Interfacial Reaction in the Dissimilar Joints Using Shape Memory Alloy Thin Wires for the Fabrication of Medical Devices Inserted in Blood Vessel

为探讨激光微细焊接技术在医疗器械制造中的应用，采用激光微点熔法对钛镍基形状记忆合金生物材料焊丝进行了微点熔化处理，通过优化激光功率或脉冲宽度等激光条件，获得了无缺陷的声点熔化焊丝，使直径为0.15 mm的焊丝熔化宽度减小到0.2 mm左右。与5U5304线材相比，形状记忆合金线材的熔化需要更精确的激光条件控制，但需要的功率较小，熔化后的金属呈现快冷组织。与母材相比，点熔焊丝的抗拉强度达到70%，超弹性行为基本相同。此外，浸泡试验和阳极极化曲线的测量证实，激光点焊NT-E4焊丝在准生物环境中仍能保持良好的耐腐蚀性，激光点焊焊丝也成功地制备出交叉或平行接头，表明激光微细焊接适用于生物医学器件的制造。

In order to investigate the applicability of laser micro welding to the fabrication of medical devices, Ti-Ni based shape memory alloy biomaterials wires were micro spot melted by using YAG laser.By the optimization of laser conditions such as laser power or pulse duration, sound spot melted wires free from any defects were prepared and the width of the melted metal was reduced to about 0.2mm for the 0.15mm diameter wires. Compared with the 5U5304 wires, melting of shape memory alloy wires needed more precise control of laser conditions although it needed smaller power input.Melted metal exhibited a rapidly quenched microstructure. The spot melted wires showed 70% of tensile strength and almost the same super-elastic behavior compared with base materials. Besides, it was confirmed by immersion test and by measurement of anodic polarization curve that NT-E4 wires still retain a sound corrosion resistance in a quasi biological environment by laser spot melting.Crosswise or parallel joints was also successfully prepared by laser spot welding of wires, suggesting the laser micro welding is applicable to the fabrication of biomedical devices.