Research On Microstructure Evolution And Electrical Properties Of Nanocrystalline Ni80Cr20 Alloy

Ni80Cr20 electrothermal alloy can be used as a new type of wire array materials in Z-pinch driver and the micro element of frozen target in laser driver. In this study,Ni80Cr20 ultrafine wires were prepared by using single-die cold drawing and continuous annealing. We studied the technical characteristics of ultrafine wire production process process. Metal wire strength machine, scanning electron microscopy(SEM), X-ray diffraction(XRD), transmission electron microscopy(TEM) and measure the resistance at low temperatures were used to research the microstructure and properties of ultrafine wire.We prepared Ni80Cr20 alloy ultrafine with 21.14 ?m by cold drawing. Then,microcontroller annealing rewinder was used as annealing equipment. We determined the optimal parameters of continuous annealing by this annealing method. It was very necessary to explore a new ultrafine wire corrosion-head and through-die method for improving the through-die efficiency in ultrafine Ni80Cr20 alloy wire preparation technology. This method used the electrochemical workstation to provide a precise corrosion time and Super Depth of Field Microscope magnified aperture of diamond dies. In this way, we resolved the difficulty of the inaccurate burn head time and manual through-die. In the drawing process, the diameter of the ultrafine wire with its grain size decreased was reduced. Work hardening and grain refinement casued the tensile strength of ultrafine wire. When the reduction rate was relatively large, elongation did not change with the reduction rate. After annealing, tensile strength of ultrafine wire gradually decreased, but the size of the grain size grew. At the same time, the elongation of the samples were increasing. The microstructure cross-section of ultrafine wire were analysed by transmission electron microscopy(TEM). Ni80Cr20 alloy had polycrystalline structure. And the microstructure of ultrafine wire had edge dislocations,twins, grain boundaries and amorphous precinct.Ni80Cr20 ultrafine wire with atomic segregation area had influence on electron scattering. From the research, we knew that the resistivity of ultra-fine were affected by the structure which were destroied by cold drawing and annealing. Ultrafine wire resistivity was mainly caused by the lattice scattering when the tempereture ranged from room temperature to 50 K. When the temperature was below 50 K, the electrons scattering played a major role.The ultrafine wire were produced by the cold drawing and annealing process. And we determinede the conditions of the drawing and annealing process. At the same time,the microstructure and electrical properties of the sample before and after annealing were studied. This research is provided reference for the preparation of the ultrafine wire.