Microstructures and properties of in situ ZrB2/AA6111 composites synthesized under a coupled magnetic and ultrasonic field

In situ ZrB2/AA6111 composites were successfully prepared from an Al- K2ZrF6-KBF4 system via an in situ melt reaction with the assistance of a coupled magnetic and ultrasonic field. The effects of the coupled magnetic and ultrasonic field on the nanoparticle distribution, morphology and tensile properties of the nanocomposites were investigated. The results indicated that with increase in the magnetic frequency and ultrasonic power to 10 Hz and 1.5 kW, respectively, the large particle clusters were broken into smaller clusters that were uniformly distributed in the matrix, the distribution of the ZrB2 nanoparticles was diffuse and homogeneous with a size decreased to 10-80 nm, and the corners of the nanoparticles clearly became obtuse. The optimal ultimate tensile strength (UTS), yield strength (YS) and elongation (El) of the composite prepared under the coupled field were 363 MPa, 240 MPa and 24.1%, respectively, corresponding to increases of 36.6%, 55.5% and 64% over the respective properties of the AA6111 alloy. The synergistic functions of the ultrasonic and magnetic fields were also discussed. The effects of the magnetic field and ultrasonic field were different.