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Herein, the ordered structure of Co-based metallic microwires was modulated by direct current-annealing, thereby improving the tensile mechanical properties. Based on the thermophysical parameters of the metallic microwires, the annealing current intensities of 65 mA, 90 mA and 150 mA were determined by the method of numerical calculation. The experimental results indicated that the ordered structure of the metallic microwires was regulated under the action of Joule heating, and with the rising of the annealing current, the ordered structure increased and the distribution tended to be concentrated. The 90 mA current-annealed metallic microwires have favorable tensile mechanical properties and fracture reliability, with the tensile strength and elongation of 4540.10 MPa and 2.99%, respectively, and the fracture threshold is 1910.90 MPa. Both the as-cast and current-annealed metallic microwires were brittle fractures, and the fractures consisted of shear deformation regions and crack extension regions. The improvement of the mechanical properties of metallic microwires is related to the nano-ordered structure and their distribution. Under the condition of 90 mA current annealing, the uniformly distributed nano-ordered structures were formed in the amorphous matrix of the metallic microwires, which can effectively slow down the expansion of the shear bands and reduce the possibility of crack generation. This study provides process reference and theoretical guidance for the application of Co-based metallic microwires in the field of stress sensors. [ABSTRACT FROM AUTHOR]

Herein, the effect of Ni-doping amount on microstructure, magnetic and mechanical properties of Fe-based metallic microwires was systematically investigated further to reveal the influence mechanism of Ni-doping on the microstructure and properties of metallic microwires. Experimental results indicate that the rotated-dipping Fe-based microwires structure is an amorphous and nanocrystalline biphasic structure; the wire surface is smooth, uniform and continuous, without obvious macro- and micro-defects that have favorable thermal stability; and moreover, the degree of wire structure order increases with an increase in Ni-doping amount. Meanwhile, FeSiBNi2 microwires possess the better softly magnetic properties than the other wires with different Ni-doping, and their main magnetic performance indexes of Ms, Mr, Hc and μm are 174.06 emu/g, 10.82 emu/g, 33.08 Oe and 0.43, respectively. Appropriate Ni-doping amount can effectively improve the tensile strength of Fe-based microwires, and the tensile strength of FeSiBNi3 microwires is the largest of all, reaching 2518 MPa. Weibull statistical analysis also indicates that the fracture reliability of FeSiBNi2 microwires is much better and its fracture threshold value σu is 1488 MPa. However, Fe-based microwires on macroscopic exhibit the brittle fracture feature, and the angle of sideview fracture θ decreases as Ni-doping amount increases, which also reveals the certain plasticity due to a certain amount of nanocrystalline in the microwires structure, also including a huge amount of shear bands in the sideview fracture and a few molten drops in the cross-section fracture. Therefore, Ni-doped Fe-based metallic microwires can be used as the functional integrated materials in practical engineering application as for their unique magnetic and mechanical performances. [ABSTRACT FROM AUTHOR]