表面纳米化0Cr18Ni9Ti/TA17加镍中间层扩散连接

Diffusion bonding of surface nanocrystallized 0Cr18Ni9Ti/TA17 using a nickel interlayer

采用高能喷丸(HESP)对TA17钛合金与0Cr18Ni9Ti不锈钢棒材端面表面进行自纳米化(SSNC)处理;采用镍箔作为中间层,在不同温度(800～875℃)下对处理后的钛合金/不锈钢进行脉冲加压扩散连接(PPDB)。对接头剖面组织进行金相观察;在拉伸试验机上测试接头拉伸强度,对断面进行SEM,EDS和XRD结构物相分析。研究结果表明:在850℃时接头拉伸强度达到最高,为322.8MPa;连接后接头界面处纳米晶粒没有完全长大,存在细晶粒区;镍箔有效地阻止了Fe-Ti脆性金属间化合物的形成,在接头处形成β-Ti,(Fe,Ni)固溶体和Ti-Ni金属间化合物(Ti2Ni,TiNi,TiNi3);断裂发生在Ni层与Ti-Ni金属间化合物界面处。

A TA17 titanium alloy and 0Crl8Ni9Ti austenitic stainless steel, surface self-nanocrystallized （SSNC） by high-energy shot peening （HESP） were joined through pulse-pressure diffusion bonding （PPDB） using a pure nickel foil at 800-875℃. Additionally, the longitudinal section microstructures of joints were studied by using optical microscope. The joint strength was tested with a tensile machine. Tensile fracture was analyzed by scanning electron microscope （SEM）, energy dispersive spectroscope （EDS）, X-ray diffraction （XRD）. The results show that the highest recorded tensile strength is equal to 322.8 MPa and is displayed at 850 ℃. The nanometer-grains across the joint did not grow up completely. Diffusion and migration between Ti and Fe atom is effectively prevented by adding pure Ni as the interlayer metal, and thus a sound joint is obtained. The interface reaction products are identified as β-Ti, （Fe,Ni） solid solution and Ni-Ti intermetallic compounds （TizNi, TiNi, TiNi3）. The specimens fracture along the reaction layer of Ti-Ni intermetallics and Ni layer.