Modification of Microstructure and Mechanical Properties of AA6082/ZrB2 Processed by Multipass Friction Stir Processing

The present work accomplished homogenously disseminated ZrB2 reinforcement particles and very fine grain structure by multipass friction stir processing (MPFSP) of AA6082. They observed the influence of reinforcement particle ZrB2 on the microstructure and tensile properties of the MPFSP. The coarse dendrite structure of the base material AA6082 was studied using ZrB2 nanoparticles. The MPFSP/ZrB2 successfully shattered these coarse and dendrite clusters, resulting in a uniform microstructure in the stir zone. The MPFSP has observed material flow around the cluster's redistribution. At increased ZrB2 concentration, SEM and EBSD examinations demonstrated that ZrB2 reinforcement particles strongly inhibited grain boundary migration, resulting in a continual reduction in grain size and HAGBs fraction. The tensile properties and microstructure of the MPFSP/ZrB2 of AA6082 were enhanced using a rotational tool speed of 1120 rpm, welding speed of 125 mm/min, and tilt angle of 2 degrees. The reinforcement particles ZrB2 were fragmented completely and uniformly disseminated in the 4th FSP pass. As the FSP increases, the ZrB2 agglomeration reduces. The base metal AA6082's ultimate tensile strength (UTS) was 191 +/- 8 MPa with a % strain of 20 +/- 0.8. After MPFSP/ZrB2 on AA6082, the UTS was increased as the FSP pass increased. The higher UTS (266 +/- 5) was observed at the 4th FSP pass.