In this paper we report a new sol–gel method for the fabrication of MgB2 films. Polycrystalline MgB2 films were prepared by spin-coating a precursor solution of Mg(BH4)2 diethyl ether on (001)Al2O3 substrates followed with annealing in Mg vapor. In comparison with the MgB2 films grown by other techniques, our films show medium qualities including a superconducting transition temperature of TC ∼ 37 K, a critical current density of JC(5 K, 0 T) ∼ 5 × 106 A cm − 2, and a critical field of HC2(0) ∼ 19 T. Such a sol–gel technique shows potential in the commercial fabrication of practically used MgB2 films as well as MgB2 wires and tapes.

5A02 aluminium alloy was joined by transient liquid phase (TLP) bonding using the two-step heating process as follows: the faying area was first heated to 600uC and kept for 5 s and then cooled down to 595uC and kept for 3 min. The microstructure and properties of the joint were investigated and compared with that of conventional TLP bond at 595uC for 3 min. The results show that the two-step heating process can produce a wave bond line that is different from the planar interface associated with conventional TLP bonding at a constant temperature. The defects at the bond line are greatly reduced, and metal to metal contacts are established along the wave bond line using the two-step heating process. Therefore, the tensile strength and bending ductility of the joint are dramatically improved.