Effects of Squeezing Pressure and Hot Rolling on (Al3Zr/Al2O3 + ZrB2)/6016Al Nanocomposites Synthesized Under Electromagnetic Field.

In situ 3-wt.% (Al₃Zr/Al₂O₃ + ZrB₂) particle-reinforced 6016Al-matrix composites were produced and squeezed at 650 °C. The effects of squeezing pressure (10–20 MPa) on the solidification microstructure and properties of the composites were investigated. Squeezed solidification of the 6016Al-matrix composites at 650 °C led to grain sizes of 65–70 µm. The synthesized (Al₃Zr/Al₂O₃ + ZrB₂) particles were segregated along the grain boundaries. Fine Mg-Si-rich Guinier–Preston zones or precipitates (~ 5 nm) were formed during solidification. Amorphous Al₂O₃ was observed adjacent to crystalline Al₂O₃ particles. The composites exhibited a lower yield strength (YS) of ~ 50 MPa because of the clustered porosity and agglomeration of reinforcement particles in hot spots (50–100 µm), formed during solidification. The composite squeezed under 20 MPa exhibited a superior ultimate tensile strength (UTS) of 186 MPa as compared to 170 MPa of the composite squeezed under 10 MPa. Mechanical properties of both the composites were improved upon hot rolling. Upon 80% thickness reduction by hot rolling, the composite squeezed under 10 MPa exhibited increase of ~ 300% in YS, ~ 30% in UTS, and 100% in fracture strain, while the composite squeezed under 20 MPa exhibited increase of ~ 260% in YS, ~ 6% in UTS, and ~ 32% in fracture strain. The improvements in properties originated from improved strengthening efficiency of (Al₃Zr/Al₂O₃ + ZrB₂) particles and homogenization of the microstructure. [ABSTRACT FROM AUTHOR]