Fabrication Of Pd₄₃Cu₂₇Ni₁₀P₂₀ Metallic Glassy Microtubes

Microtubes with specific hollow structure possess low density,large specific surface area,and strong load capacity,as well as wide applications in optics,electricity,magnetism,sensors,biomedicine,and so on.Those tubes can be fabricated by using different raw materials,including carbon materials,oxide glasses,metals,ceramics,and polymers.The characteristics of the materials determine theperformance and application of micro-and nanotubes.Therefore,a high-performance metallic glass was selected as the raw material.And a novel instrumentation wasdesigned for the preparation of metallic glassy microtubes.The succeed fabrication of metallic glass microtubes will attract research interests and extend engineeringapplications of metallic glasses and microtubes.In the present work,we developed a synthetic technique for production ofmetallic glassy microtubes?MGMTs?by drawing bulk metallic glass tubes in their supercooled liquid region via thermoplastic forming.The Pd₄₃Cu₂₇Ni₁₀P₂₀ MG alloy was selected to fabricate the MGMTs due to its strong metallic glassy fibers forming ability?FFA?.The bulk MG tubes which was used as pre-form of microtubes were prepared by using a drilling machine.The Pd₄₃Cu₂₇Ni₁₀P₂₀ MGMTs with single hole and multiple holes were prepared in a vacuum chamber with induction heating coil.The single-hole microtubes with smooth surface are uniform and continuous,but the surface of the microtubes with multiple holes is rough and deformed obviously.At the same time,the repeatability and success rate were relatively low.In order to solve the problems,a new instrumentation with a tungsten wire heating coil,a computer heating controlling program,and a vacuum chamber was designed for the preparation ofmetallic glass microtubes.The preparation process can be precisely controlled by the computer program.The heating source is a refractory tungsten wire coil with aaxisymmetric thermal field.The inner diameter of the prepared single-holePd₄₃Cu₂₇Ni₁₀P₂₀ metallic glassy microtubes were relatively thin?minimum inner diameter is about 3?m?.Furthermore,the heating time became shorter as the initial heating current increased.In addition,the Pd₄₃Cu₂₇Ni₁₀P₂₀ metallic glassy microtubes are fully amorphous confirmed by XRD and TEM structural characterization.The 3D microstructure of the single-hole MG microtubes were characterized and reconstructed by using synchrotron X-ray nano-CT.It was further proved that thisnew instrumentation and fabrication technique for preparing metallic glassymicrotubes is feasible.The sample has a good cylindrical structure without obvious deformation,and the success rate of this method was improved a lot.Through the analysis of the gray value g of the reconstructed sample,it was found that the metallic glassy microtubes have density fluctuations at the micrometer to the nanometer scale.Moreover,the metallic glasses can be regarded as a heterogeneous material withlow-density regions and the high-density regions.The inner and outer surfaces of the microtubes possess the lowest density,resulting from the excess free volume of the surface area which is subject to surface tension.The density fluctuation furtherconfirmed the microstructural heterogeneities of metallic glasses.