Microstructure and Jc-B performance of powder-in-tube MgB2 wire made by using Mg2Cu powders with low melting point

MgB4 superconducting wires can be synthesized through a new route by Using Mg2CU instead of pure Mg. The brittle Mg2Cu compound can be easily broken into the fine powders by a mechanical grinding. In addition, its melting point are lower than that of pure Mg, thus the diffusion reaction for synthesizing MgB2 may be promoted through their liquid states. Both of J(c) and B-irr at 4.2 K improved apparently with decreasing the size of Mg2Cu powders as a starting material. 100 A/mm(2) was obtained at 4.2 K and 4 T on the Fe-sheathed MgB2 wire made by Using Mg2Cu powder with a diameter of a few microns. These improvements may be due to the enhancement of homogeneity of the powder mixture. According to the STEM observation, a lot of small MgCu2 particles with a size of about 10 nm were dispersed in the MgB2 matrix synthesized through a fine Mg2Cu powders. They may act as the pinning centers in the present MgB2 wires.