In this paper, both the tensile deformation behaviors and mechanical properties of in situ ZrB 2 nanoparticles reinforced AA6016 matrix composites are investigated with finite element analysis. For the modeling, the volume fraction of nano ZrB 2 particles is defined by combining cluster sizes with particulate agglomerated degree which was observed in the agglomeration clustered regions by experiments. The effects of clusters on the mechanical behaviors of composites are disclosed according to qualify mechanical behaviors of local particulate agglomeration. The results indicate that finite element analysis is performed to predict the Young's modulus of composites, which is in good agreement with the experimental results. In addition, the speed of stress concentration is faster when the agglomerated degree elevates, which minimizes elongation of composites under the same particle volume fraction. Likewise, under the same agglomerated degree, the higher particle volume fraction of composites triggers the reduction of elongation.

ZrB 2 and Al 2 O 3 nanoparticle-reinforced aluminum matrix composites were successfully prepared by in situ chemical reaction of the Al-Na 2 B 4 O 7 -K 2 ZrF 6 system with magnetic field applied in the in situ reaction and ultrasonic field introduced in solidification. The results indicated that the optimized magnetic frequency was 10 Hz, and the ultrasonic power was 1.0 kW. XRD analysis showed that ZrB 2 and Al 2 O 3 nanoparticles have been obtained. The smaller clusters were evenly distributed in the matrix. ZrB 2 and Al 2 O 3 nanoparticles were dispersed and uniformly distributed. The average size of particles and grain size of (ZrB 2 +Al 2 O 3 ) np /AA6111 composites were refined to 45±10 nm and 50.4±12 μm, respectively. The maximum Vickers hardness, tensile strength, yield strength and elongation of the composites synthesized under the optimized magnetic and ultrasonic fields were 142.2 HV, 355.4 MPa, 259.4 MPa and 22.4%, which were 1.34, 1.36, 1.35 and 1.33 times higher than that of AA6111 alloy, respectively.

The hot deformation tests of in situ ZrB 2 and Al 2 O 3 nanoparticles reinforced AA6016 matrix composite were studied at deformation temperature of 300°C-450°C and strain rate of 0.001-1 s −1 . In this paper, the ZrB 2 and Al 2 O 3 nanoparticles were successfully prepared by direct melt reaction method firstly. Based on experimental results, the flow stress increased rapidly with the increasing true strain and decreased with the increasing temperature. Constitutive equation of the composite can be established based on the Arrhenius constitutive model. The processing map based on dynamic material model showed two stable processable domains: Domain A(300-360°C/0.08-0.01 s −1 ), which was controlled by dynamic recovery and domain B(410-430°C/0.37-1 s −1 ), which was typical dynamic recrystallization structure. The microstructural changes of the samples after deformed were observed through optical microscope (OM), scanning electron microscope (SEM) and transmission electron microscope (TEM). It was concluded that these two kinds of reinforced particles can greatly promote recrystallization nucleation at high temperatures. Thus, domain B is optimum hot processing window.

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